Advanced NFL Stats

Paying Free Agent RBs

2012-03-05T07:00:00.000-05:00

Ray Rice, Matt Forte, Payton Hillis, Marshawn Lynch, and Arian Foster were all due to become free agents this off-season. Rice and Forte have already been franchise-tagged, and Foster is a restricted free agent. Still, the question of what they're worth in terms of salary and cap space remains.

A couple months ago, I took a look at the safety position and how free agents are paid. And more recently I took a look at how QBs are paid with the intent to eventually establish a rational framework for how they should be paid according to their actual production in terms of wins and points. Like the prior analyses, my primary goal for now is to get a feel for the market.

As in all individual player analysis, it's worth stating up front that football is always a team sport. Like all other positions, a RB's stats are not his alone, as they depend heavily on offensive lines, opponents, scheme, situational variables, passing game strength, and other considerations. We can account for the situational variables with the EPA and WPA models, but we must rely on the tendency for factors beyond the control of the individual player to even out in the long run. They may not even out for any individual RB, but in aggregate, the idea is that some RBs will have above average lines, some will have poor lines, and collectively we can roughly estimate the financial value that a RB brings his team based on production.

First, let's take a look at how RB salaries are actually determined. There are two graphs below. The first plots career total rushing yards vs. career total cap hit. The second plots career Yards Per Carry (YPC) vs. career cap hit. The data include years 2000-2009 and is limited to RB seasons with greater than 6 game appearances and greater than 50 carries. Cap hit is adjusted for NFL inflation. Only players who had a cap hit greater than $1M in year 2000 dollars were considered. This limitation is so that we sample only high-priced RBs, and is necessary to see any relationship at all between performance and pay.
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If only...

2012-02-07T15:13:00.000-05:00

Another post at the Slate/Deadspin rountable.

Any of these five plays could easily have gone the other way. In total they represent 0.73 WP—nearly the entire difference between winning and losing. Win probability is obviously an abstract concept, but it helps put a concrete number on what we already intuitively understand. Numbers like this underscore how razor-thin the difference between winning and losing is, especially when the two opponents are evenly matched. This year's Super Bowl was like most other NFL games—it hinged on a handful of critical and unusual events. The conference championship games were no different: The Giants won thanks to two bungled punt returns by the 49ers, and the Patriots won in large part thanks to a missed 32-yard field goal attempt by the Ravens.

If you missed my first one from Sunday night, here's the link. It covered the end-game strategy decisions of allowing the final TD.

The smartest play of all would've been for Belichick to have allowed the touchdown even earlier. The Patriots certainly could have done so on the play prior to Bradshaw's touchdown run, when he was stopped for a one-yard gain, forcing New England to burn its second timeout. In fact, they probably should have allowed a touchdown as early as the two-minute warning. That’s the point at which the Win Probability of receiving a kickoff down by four or six points (0.23) exceeds the Win Probability of trying to stop the Giants from bleeding the clock dry (0.2). The Patriots would have had almost two minutes, two timeouts, and all four downs available to get a touchdown and steal the win.

Ring Probability Added

2012-02-07T10:06:00.002-05:00

...by Joe Harris over at the Community Site.

More Super Bowl Analysis

2012-02-06T15:19:00.000-05:00

Comparison to Broncos – Packers in SB 32

Many people are pointing out the similarity between last night's final touchdown and the situation in Super Bowl 32 between the Packers and Broncos. I’ve previously written about that game, and I agree that the right thing to do was to allow Denver to score. With about 1:47 to play and the score tied at 24, the Packers allowed Tyrell Davis to walk into the end zone for the go-ahead score. The Packers got back possession but were unable to move the ball on their first series of the drive. The Broncos went on to win.

So why should Belichick’s decision to allow the touchdown be considered gutsier than Holmgren’s? The primary reason is that in Belichick’s case, his team had the lead. The Patriots strategically forfeited a Super Bowl lead. Had they forced a field goal attempt and it was missed or blocked, the Patriots would have won the game. In Holmgren’s case, the best case scenario for the Packers was a tie. Had they held the Broncos scoreless at that point, they still would have likely needed overtime to win.

Although the ultimate effect was the same in the two situations, the notion of intentionally forfeiting a lead is qualitatively distinct from allowing a team to break a tie. It’s instinctively more difficult, and therefore I believe required ‘more guts.’ (Or in Deadspin parlance, it was "ballsiest".)

The second reason was the game situation. The Broncos had a second and goal at the 1 with about 1:47 left on the clock, and a touchdown was a very likely outcome anyway. In the Patriots’ case, a Giants touchdown was far less assured. Belichick’s decision also relied on the faith that the Giants would not take a knee at the one as they should have. From the 1, there was no risk that the Broncos could get any closer, making the FG any shorter.

Was the Giants’ 12th man penalty intentional?
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Super Bowl 46 Analysis

2012-02-06T00:27:00.000-05:00

This became a really interesting game in the final two minutes.

First off, as I wrote for Slate and Deadspin, the big thing from a strategy perspective was the final go-ahead touchdown of the game. Belichick may have made the gutsiest call in Super Bowl history by apparently instructing his defense to allow the score with a minute to play. Had the Giants run out the clock in favor of a chip shot field goal, it would have extinguished any chance the Patriots had. Instead, they had a minute and one timeout to respond. It wasn't clear if Bradshaw was tippy-toeing trying to go down at the one, or if he was just burning a couple extra seconds prior to scoring like video-gamers are know to do. Either way, he should have taken a knee.

Beyond that, Eli Manning was a defensible choice as MVP, with 0.70 WPA and 12.3 EPA. But I thought the real difference in the game was the battle in the trenches. The NYG defensive front won the battle, handing the NE offensive line -0.24 WPA and -0.4 EPA. They had only 2 sacks, but more importantly they put Tom Brady on the ground 7 times. They added four tackles for losses and held the NE running game to a lower than typical success rate.

The big stars on the NYG defense were Justin Tuck and Jason Pierre-Paul. Tuck had 0.24 +WPA, 4.7 +EPA, and a Success Count (SC) of 4. Pierre-Paul notched 0.20 +WPA, 5.1 +EPA and a 6 success plays. Blackburn made the one interception of the game, but it was so deep it didn't move the needle very much. He made a bigger impact with his tackles, earning a 1.14 Tackle Factor for the game.

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WP Forfeited

2012-02-04T23:10:00.000-05:00

It's 4th and 2 from the opponent's 42. The score is tied at 17. There's 1 minute and 17 seconds left on the clock. What would you do? If you're Ken Wisenhunt, you send in Dave Zastudil to punt.

One thing I've learned about human nature is that to help convince someone of something, I should frame the issue in terms of fearing a potential loss. That's usually a stronger motivation than expecting a potential gain. For example, I wouldn't suggest to a coach that he could improve his chances of winning by going for it on 4th down more often. Instead, I'd tell him he's forfeiting a significant chance of winning by not going for it. Nobody likes forfeiting stuff. My wife suggested using the phrase "leaving points on the table." Coach Wisenhunt forfeited 13% chance of winning that game.

By far, the most common question I get from reporters is whether teams are going for it more often. My answer is almost always "it's complicated, but I think so." The difficulty in measuring 4th down aggressiveness is that it's so dependent on the situational variables. You can't just count how often teams go for it rather than kicking. To-go distance, score, and time all weigh heavily on the decisions, and there are just too many possible combinations to compare rates from year to year or even decade to decade.

If we constrain the analysis to certain parameters--inside opponent territory and when the score difference is within reason, for example--we'd get an incomplete picture. We've learned over the last few years that there can be many situations outside traditional 'go-for-it' limits in which it can be beneficial to go for the conversion rather than kick or punt. And each situation can have a drastically different magnitude of effect on a team's chances of winning. Also, why would we reward a coach if he goes for it on 4th and whatever when he's down by 5 with a minute left to play? Coaches always do that.

Here's my stab at the problem. With every 4th down situation in which it would usually make sense to go for it but a coach decides to kick, he forfeits some amount of win probability. We can total all the WP forfeited to measure the degree to which teams are erring on the side of conservatism.
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Air Yards 2011

2012-01-29T23:00:00.000-05:00

Imagine that football were just invented and we had to figure out how to credit passers with all the yards they generate, and I said let's include all the yards that the receiver runs after the catch. I'd be laughed out of the room. But that's the convention we've been handed.

It's not that QBs shouldn't be credited at all, because if a pass isn't completed there can be no yards after catch at all. And the argument that a very accurate QB that can hit a receiver in stride or lead him to open space to create YAC can't be ignored. Scheme matters too. But it's evident that some QBs feast on the YAC-gaining abilities of their receivers much more than others, distorting their overall stats.

I came up with Air Yards a few years ago as a method to compare passers with their receiver's YAC removed. Air Yards is simply the complement of YAC. It's the yardage a pass travels through the air forward of the line of scrimmage. AY is a unique and interesting way to view QB performance, but it's not perfect. A QB would be penalized for completing a short screen that's caught a yard to two behind the line of scrimmage. But those plays are few and far between, and I don't lose any sleep worrying about them. We should also keep in mind that a QB's performance is never just his own. But AY might be an inch closer to isolating the individual QB's contribution than if we look at total passing yards alone.

Here are the leaders in AY for the 2011 regular season. The table is sorted by default according to Air Yards per Attempt (AirYPA), but you can re-sort the table by clicking on the column headers.
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Sterling Moore and Split-Play WPA

2012-01-26T06:00:00.000-05:00

Sterling Moore posted a stellar +0.47 +WPA in Sunday's AFC championship game. That's very good -- only Patrick Willis (+0.52) and teammate Dane Fletcher (+0.49) beat that mark for defenders on championship weekend. After all, Moore made arguably the defensive play of the weekend when he knocked what would have been the go-ahead touchdown pass out of Lee Evans's hands with mere seconds to go.

But most of Moore's +WPA actually comes from his contributions on the following play, the failed third down pass targeted for Dennis Pitta which set up the fateful fourth down on which Billy Cundiff kicked the Ravens out of the playoffs. The Ravens were still in excellent shape on that third down, and the failure to convert or score a touchdown took their win probability down from 83% to 43%, giving Moore a +0.40 WPA on the play. That leaves just +0.07 for his other successful play, the strip of Evans in the end zone.

That seems intuitively way too low, and that intuition is correct. Although technically the entire play from snap to throw to almost-catch to strip just cost the Ravens 7% of a win, if Evans holds on to the ball and Moore doesn't strip it, Baltimore's ticket to the Super Bowl is all but punched. But with the way the data is fed into our system, it's impossible to give out separate credit for different aspects of plays.

But let's say for a second it was possible. How would each aspect of that play have played out in the eyes of WPA?
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On Opponent Strength and Team Strength Correlation

2012-01-25T17:37:00.000-05:00

This post at Football Outsiders caught my eye today. The IgglesBlog noticed something odd with their team rankings. I’ve notice the same phenomenon in my own systems—that team ranking methods that adjust for opponent strength tend to produce rankings that correlate (inversely) with a team’s strength of schedule. In other words, top ranked teams appear to have weaker schedules and low ranked teams appear to have stronger schedules. The problem is, assuming that a ranking method properly adjusts for opponent strength, it ostensibly should produce no correlation between each team’s ranking and its opponents' average ranking. In fact, we might expect the opposite result because of the two “strength of schedule” games each season—Last year’s 1st place teams play other 1st place teams, and so on.

In 2011 FO’s “DVOA” method correlated with opponent strength at -0.66, which is considerable. Here at ANS, Generic Win Probability correlated with Average Opponent GWP at -0.60 this season. FO notes that in other years the correlation isn’t nearly as strong, but there is an apparent tendency for negative correlations for most seasons.

This phenomenon was first pointed out to me a couple years back by a reader, and I too thought it was either a) randomness, or b) a flaw with my methodology. But I soon realized this is exactly what we should expect given the NFL’s scheduling rules. It’s neither luck nor a flaw. In fact, it's a sign the method is doing something right.

Consider a fictional four-team football league. Presume we have a perfect team ranking system that can peer omnisciently into each team’s soul to know its True Winning Probability (TWP). The Sharks, Knights, River Dogs, and Jack Rabbits each have a TWP of 0.75, 0.60, 0.40, and 0.25. (Notice the TWPs average to 0.50, as they would have to.)
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Should The Niners Have Kept The Punt?

2012-01-23T09:19:00.000-05:00

Who would have thought that Ted Ginn Jr.'s absence might have made all the difference in the NFC championship game? Kyle Williams' two fumbles on punt returns kept the Giants in the game and all but won it for them in OT. During the course of this 22-punt game, Jim Harbaugh was forced with a few 4th-down decisions. Earlier this year, Brian wrote about Harbaugh's decision to keep the 3 points after David Akers made a 55-yard field goal and the Cowboys were called for a 15-yard penalty. In the third quarter, down 10-7, the Niners were faced with a similar conundrum, this time with a punt. On 4th-and-6 from midfield, Andy Lee hits a beautiful punt the to the Giants' 7-yard line. Justin Tuck is called for running into the kicker, but Harbaugh declines and takes the punt, pinning the Giants deep. But, was this the right decision?

After the punt, the 49ers win probability was 37% (and their expected points were +0.34, meaning they were actually expected to be the next team to score even though the Giants had the ball). So the question is as follows: does going for it on 4th-and-1 after the penalty increase the Niners' chance of winning? The estimated success rate on 4th-and-1 is 74%. If San Francisco succeeds, their win probability jumps to 47%; if they fail, it falls to 31%. So, if we let x be the chances of converting on 4th-and-1, we have the equation 0.31*(1 - x) + 0.47*x > 0.37. Thus, the 49ers should go for it if x > 37.5%. Since the estimated conversion rate is 74% (almost twice our break even point of 37.5%), this seems like a no-brainer: the correct decision would be to take the penalty and go for it.
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Roundup 1/21/12

2012-01-21T12:08:00.000-05:00

Using portfolio theory to analyze fantasy football strategies. I tinkered with portfolio theory a while back, but ultimately understood it's not appropriate for real football analysis. It is however, well-suited for fantasy analysis.

A commenter linked to this a couple weeks ago. Correlation != causation.

2011 Giants = 2010 Packers? I buy that.

A different kind of look at Flacco.

Is the new rookie wage scale the reason for the record number of underclassmen declaring for the draft?

This is a good analysis of when teams ahead should try to score rather than run out the clock. I agree and made the same observation at the time on the WP graph comments. Fans and analysts typically call for teams to 'run out the clock' far too early. The sport has changed over the years to where offenses only need 1 minute to drive the length of the field for a TD. The 2-minute drill is an antiquated term. Two minutes is an eternity. (See the NO-SF game: 4 TDs in the 4 final minutes.) Helmet-knock: FO.
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And Then There Were Four

2012-01-20T19:44:00.000-05:00

A lot of media attention naturally goes to the quarterbacks at this point in the season. Much of it this week has shone on Joe Flacco in particular. While it's true he didn't light up the scoreboard like the other three QBs did last week, he was the only one playing against one of the league's best defenses. The others faced the 17th, 22nd, and 29th ranked defenses in terms of overall efficiency. A lot of the debate on Flacco has revolved around the notion that he just wins. I hear a lot of people cite his overall win-loss record as a starter as well as mentioning he has a very good defense backing him up. On one hand he's been to the playoffs 4 out of his 4 seasons, but on the other he's not the reason the Ravens win.

Win Probability Added seems it was made to settle debates just like this. And WPA says that since his second season in the league, Flacco is one of the main reasons why the Ravens have been a winning team. In fact, over his entire career his WPA has averaged +0.10 per game. And his last two seasons were +0.21 and +0.19 WPA, well above average. In other words, his performance would make a .500 team a .700 team, all other things being equal. But not everything is equal. In particular, quarterbacks naturally have positive WPA simply because passing is more lucrative than running, plus it's been getting easier over time.
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Running in the Cold

2012-01-19T19:35:00.001-05:00

A few posts ago, we looked at how temperature affected the passing game. This time, we’ll look at the running game. Often, analysts will discuss how winds and cold might affect passes, but unless the conditions are exceptionally snowy or muddy, rarely does anyone consider how cold weather affects running. And why would they? I’d agree there isn’t much reason to suspect that cold temperature alone would cause runs to be any longer or shorter than in moderate weather.

Before we look at the numbers, I should note that running and passing are connected in game theory terms. The better a team’s passing attack, the more an opposing defense needs to respect it, possibly allowing bigger running gains. And same goes for a great running attack. The better it is, the more the defense needs to be on guard near the line of scrimmage, lowering its guard against the pass.

Cold temperatures, or at least the kinds of conditions that go along with cold temperatures, appear to reduce the effectiveness of passing. With that in mind, defenses might be worried slightly less about deep passes and stack the box in cold temperatures. Thus, we might expect that cold temperatures could indirectly reduce the effectiveness of running.

This is where it gets really interesting, because that’s not what happens at all.
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Conference Championship Game Probabilities

2012-01-19T13:58:00.002-05:00

Weekly game probabilities are available now at the nytimes.com Fifth Down. This week, I discuss some considerations about how the four teams are perceived, including factors like recency bias and the randomness of turnovers.

Postseason Projections: Conference Round

2012-01-17T13:07:00.000-05:00

We'd previously warned that the eventual winner of the NFC East was not to be underestimated in the postseason, and the Giants showed why in last Sunday's win over the Packers. By a slim margin, the model now sees the Giants as the strongest of the four remaining teams, though their advantage is lessened by the fact that they will have to meet the 49ers on the road. Overall, the model now gives New York about one chance in three to win the Super Bowl, odds on par with those of the Patriots.

None of the remaining teams is particularly dominant at this point and none is a complete long shot. San Francisco, with the lowest probability of a Super Bowl win, is still given a 15% chance. And now, submitted for your approval, the final postseason projections of the 2011 season, with the table below listing each team's percent probability—first of advancing to the Super Bowl and then of winning the whole thing. Enjoy.

Percent Probability to Advance
Team	Super Bowl	Sup Bowl Champion
NE	64	35
BAL	36	18
SF	41	15
NYG	59	32

Temperature and Field Goals

2012-01-17T07:00:00.000-05:00

As a pilot, I'm familiar with the effects of weather on things hurtling through the air. Many people intuitively sense hot, humid air as thicker and heavier, but the opposite is true. Warm air, as we all learned in 5th grade, is less dense than cold air. And the water molecules that make air humid, for some reason I've long forgotten, actually spread all the other molecules out, creating even thinner air. Aviators are wary of the Four H's--hot, humid, high (elevation), and heavy--things that can drastically alter performance and make takeoffs and landings a challenge.

Planes, and jet planes in particular, love cold dry air. The dense air helps engines work efficiently, and it helps the wings produce lift, making for shorter takeoffs and slower landing speeds. Baseballs, on the other hand, love the Four H's. Fans of our national pastime are well aware of the fact that home run rates peak in the hottest months of the season, and that balls tend to fly out of the park in Colorado.

Field goal kicks are affected by the same factors as anything else flying through the air--wind, temperature, and even altitude. In this post, we'll take a look at how temperature affects field goal success.
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Team Stat Visualizations Updated

2012-01-16T14:17:00.001-05:00

The team stat visualizations are now updated through the division round. If you're looking for analysis of recent trends for the four remaining teams, this is all you need. Use the slider bar to filter out however many weeks you like from the early half of the season, and see how the teams compare on the grid.

Are the Giants really winning in the past several weeks thanks to their defense?
Which team is the only remaining in the playoffs with both an above average offense and defense?
Check out just how far off their games both the Saints and Packers fell this past weekend.
Have the Patriots really righted their defensive ship since mid-season?
Which team won this past weekend despite their 3rd worst offensive output of the season?
How do the four remaining teams compare in terms of passing and running EPA per play, on offense and on defense?

Alex Smith Sheds The Dilfer Name

2012-01-16T11:45:00.000-05:00

Earlier this year, I introduced the Trent Dilfer Club - those quarterbacks for good teams who don't typically win games for their teams, but can often lose them. The Club members typically win by limiting their self-destruction and managing the game. This year, nobody followed this concept better than Alex Smith. Among QBs who played at least 9 games, Smith led the league with only 5 interceptions all year (and he played all 16 games!). He added a measly +0.01 WPA per game, but the 49ers entered the playoffs as the number two seed in the NFC with a 13-3 record.

Enter the divisional round. The 49ers are 3.5 point underdogs at home to the hottest team in football, the New Orleans Saints. The only possible way for the Niners to win would be a dominant defensive performance, right? Wrong. Alex Smith made throw after throw - mostly to his favorite target Vernon Davis - keeping the 49ers in one of the most exciting and high-scoring fourth quarters in playoff history. If I told you the Saints would score 32 points, no one would believe San Fran to come out on top. Check out Alex Smith's WPA and EPA/P throughout the course of the season:

Sunday's Division Round Analysis

2012-01-16T00:22:00.002-05:00

Here are some quick reactions to Sunday's division round games, with at least one statistical morsel from each game. Click the game header to see the graph and advanced box score.

HOU at BAL

The Texans outplayed the Ravens in almost every way except one--turnovers. Jacoby Jones' muffed punt was the costliest. With a 3-point lead in the 1st quarter, the HOU defense forced a 3-and-out. On the ensuing punt, Jones watched the ball bounce in front of him, but made a play for the ball to save field position. The Ravens recovered it at the HOU 6 and went on to score a TD. If you look at the WP graph, it was the signature play of the game, and HOU never fully recovered.

This game was supposed to feature two of the league's premier runners. Instead, it was all defense. Arian Foster had 132 yds on 27 carries (4.9 YPC), but netted -0.01 WPA and only 1.8 EPA. Why? Failures at critical plays. Foster was killed for a 7-yd loss by Ray Lewis on a flare pass forcing a 2nd and 17 when HOU only trailed by 4. On the next play, he was strung out of bounds for just a 1-yd gain, creating a 3rd and 16. On a 3rd and 1 at the BAL 21, Foster was stuffed for no gain. And so on.

Ray Rice did much worse. He was stuffed on several critical goal line plays. And on a 2nd and 1 to seal the win, he was stopped short of the marker. Rice finished with -0.15 WPA and -6.3 EPA. These lunatics at the Baltimore Sun who week-in and week-out clamor for more carries by Rice, who cite fallacious 'when Rice gets 25 carries the Ravens win' stats, need to get a clue. (I'm looking at you Mike Preston.) A long time ago I came to the conclusion that most sports desks at our major city papers don't have the first idea about the sport on which they claim to be so authoritative, but the Baltimore Sun is in a league of its own. Those guys seem like nice folks, but...they have a duty to educate themselves. It's their job. As it is, they're no better than the average fan with his harebrained opinions.
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Saturday Division Round Analysis

2012-01-16T00:18:00.003-05:00

Here are some quick reactions to Saturday's division round games, with at least one statistical morsel from each game. Click the game header to see the graph and advanced box score.

NO at SF

This was the most exciting of the weekend's games, with a 7.6 Excitement Index. SF had an incredible 1st quarter, taking a 17-0 lead. They clung to those 17 points like life depended on it until Akers hit a 3rd quarter FG to make the game 20-14. Things didn't look so good for SF with 4 min left in the game. Yes, they were up by 6 against NO. But, they were only up by 6 against NO. That's when the explosion occurred. All football hell broke loose. There was one touchdown per minute in the final 4 minutes of the game, 2 per team.

Vernon Davis will be immortalized with his amazing catch on the goal line for the win, but he racked up huge chunks of WPA well before that moment. His 47-yard catch to get the NO 20 was a 0.45 WPA play, and his 37-yarder on the prior TD drive was a 0.39 WPA play. If I'm game planning for the Giants this week, I'm going to take away Davis.
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Live WP Graphs and Analysis

2012-01-15T17:00:00.001-05:00

Keep up to speed with the live WP Graph for the NYG-GB game. Everyone's invited to join the commentary and analysis thread.

Roundup 1/14/12

2012-01-14T05:00:00.000-05:00

When it comes to passing, there's the Packers, Saints, and Patriots, and then there's everyone else.

Tebow is no good, except when he's great.

PFR's AV for 2011 is up.

The future of prediction.

From the Community Site: Bayesian Coach Rankings by David Durschlag. Also, Jim Glass keeps it simple.

Michael Beuoy has also updated his 'futures' market rankings, which I think is very clever. Michael has also recently launched his own site. Check it out.

The NFL continues to be competitively balanced.

The effect of the kickoff rule change.
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Weather Effects on Passing

2012-01-13T07:00:00.000-05:00

My last post looked at the effect of temperature on home field advantage. We saw that cold weather put dome and warm climate teams at a disadvantage. The post was titled How Does Temperature Affect Road Teams?, but I really didn't answer that question. I measured the size of the effect, but I didn't solve the riddle of actually how temperature makes a difference. This post will begin to look at just how weather makes a difference, starting with the passing game.

Here's how passing fares for home and visiting teams by temperature. The chart below shows Adjusted net Yards Per Attempt (AYPA), which accounts for sacks and interceptions, according to temperature. Keep in mind there are smaller sample sizes at the extremes.
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Division Round Game Probabilities

2012-01-12T12:52:00.000-05:00

Weekly game probabilities are available now at the nytimes.com Fifth Down. Again, this week I share some statistical tidbits on all four of the match-ups.

How Does Temperature Affect Road Teams? (And Dome Teams in Particular?)

2012-01-12T07:00:00.000-05:00

A few years ago I looked at how well teams from various climates types played when visiting other climate types. The most remarkable result was that dome teams win only about 20% of the time when playing in the cold. But that study was limited in several ways. Instead of actual temperature data, I used December in a cold-weather city as a proxy for cold temperature. I also was limited to regular season games from 2002 through 2006.

With new and better data, I redid the study. This time I have actual temperatures and used all non-preseason games from 2000 through the wildcard round of the 2011 season (last Sunday). Here are the results. The graph below depicts the winning percentage of the road team by temperature at kickoff. Road teams are classified according to their home climate--dome, cold, moderate, or warm.
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