Can Barcelona come back?

2010-04-28T00:00:00+00:00

Barcelona are 3-1 down going into the second leg of the Champions League semi-final against Inter Milan. Once again I feel roused to check the stats to see how likely a team is to come back in the second leg of a tie. The same caveat applies as for the previous study, namely that the size of the sample is limited. Fewer first leg games have finished 3–1 than have finished 2–1. There’s nothing to be done so we will just work with what we have.

The Raw Data

I’m using the same data source as I did last time, my CSV file of the RSSSF European Cups Archive. The data has been updated to include the quarter-final ties from the last round, meaning that it now contains the details of 1,454 two-legged ties played in the competition since the full introduction of the away-goals rule for the 1968–1969 season.

The Methodology

In a similar fashion to the previous look at the data I’m going to look at the first-leg games which finished in a 3–1 victory for the first-leg home team and then find out what percentage of these ties resulted in an eventual win for the first-leg home team (henceforth “home team”), first-leg away team (henceforth “away team”), or a draw¹.

I have maintained the 3-period reporting structure from the previous study. These are since the introduction of away goals in 1968 (53 ties), since the re-branding of the competition in 1992 (29 ties), and the first 29 ties which had a first-leg which finished 3–1 since 1968.

The Processed Data

The results for the 3 periods chosen are as follows:

Outcome of ties finishing 3–1 in the first leg
Period	Ties	Home Team Win %	Draw %	Away Team Win %
1968–2010	53	75.47	1.89	22.64
1992–2010	29	79.31	0.00	20.69
1968–1997	29	68.97	3.45	27.59

The worst for away teams, based on the above figures, is 20.69% in the Champions League period; all for a winning chance. This means that in the 29 ties since the Champions League re-naming in which the first-leg has finished 3–1 the away team has come back to win only 6 times, and has never taken the tie to penalties.

In the period since the away goals rule was introduced the away team has had a slightly better record, with a 24.53% chance of recovery; a 22.64% chance of winning outright, along with 1.89% chance of taking the tie to penalties.

The best record was in the period from the introduction of away goals in 1968 up to 1997². During that time the away team went on to make at least a penalty shoot-out 31.04% of the time.

The Conclusion

Once again the sample size is small but the numbers seem reasonable. The average team has at best about a 31% chance of recovering from the position Barcelona are now in, and Barcelona are by-no-means an average team.

They might do well to take heart from the fact that 2 out of the 6 recoveries from this position, since the Champions League began in 1992, have been achieved by the club; against Dynamo Kyiv in 1993, and Chelsea in 1999. Both also involved the conceding of an away goal in the home leg, so that is not a fatal blow if it happens again. It’s unlikely that Barcelona can recover but there is a chance, and history shows that they have done it before.

To repeat myself from before; I defined a draw to be a tie which is level at the end of playing time, before penalties, where no team wins on away goals. I decided to regard games which went to penalties as draws for statistical purposes as it seems improper to regard them as clear home or away wins. Feel free to disagree, good arguments may persuade me to re-think.↩
There is a period of overlap between the two 29 match periods. The first 5 ties of the Champions League period and last 5 ties of the earlier period are the same due to the limited number of ties to work with. These 5 ties resulted in 3 home and 2 away wins.↩

Champions League Post-First Leg Expectations

2010-04-06T00:00:00+00:00

I’ve long held the belief that a single goal loss, away from home, in the first leg of a two-legged tie is a decent result, especially if the away team scores. A comment by Jamie Redknapp¹, claiming that a 2–1 first-leg away loss by Manchester United to Bayern Munich was “a disaster”, convinced me to use data to check the validity of both of our positions. Rather than getting distracted by various permutations I decided to check the Redknapp case, the likelihood a team has of recovering to win, or draw, a tie if it loses the first leg 2–1.

The Raw Data

As my interest was sparked by a Champions League result I decided to look at the previous results of the competition (including the European Cup), specifically all two-legged ties played since the full introduction of the away-goals rule in the 1968–1969 season. This, I hoped, would give me a reasonable number of games from which to make a judgement.

After much searching for a nice, clean source for that data I finally resorted to using the RSSSF European Cups Archive². A few happy hours parsing the HTML of the archive with perl later³ I had a CSV file⁴, containing the 1,450 two-legged ties⁵ played in the competition since 1968.

The Methodology

In order to test the “Redknapp Hypothesis” I needed to identify all of the first-leg games which finished in a 2–1 victory and then find out what percentage of them resulted in an eventual win for the first-leg home team (henceforth “home team”), first-leg away team (henceforth “away team”), or a draw⁶. If the “Redknapp Hypothesis” holds true then the home team in the first leg should go on to win the overall tie by a overwhelming margin, with the away team winning rarely.

I initially decided to calculate this for 2 periods, since the introduction of away goals in 1968, and since the re-branding of the competition in 1992. Following this calculation, shown below, I added a further data set, the first 51 ties which had a first-leg which finished 2–1 since 1968. This final set was to provide a comparison to the second set which also contained 51 games.

The Processed Data

The results for the 3 periods chosen are as follows:

Outcome of ties finishing 2–1 in the first leg
Period	Ties	Home Team Win %	Draw %	Away Team Win %
1968–2010	116	48.28	3.44	48.28
1992–2010	51	56.86	1.96	41.18
1968–1984	51	41.18	3.92	54.90

The worst for away teams, based on the above figures, is 43.14% in the Champions League period; a 41.18% chance of winning outright, along with 1.96% chance of taking the tie to penalties. In the period since the away goals rule was introduced the away team actually has a 51.72% chance; in that period the teams have won exactly the same number of ties after a 2–1 first leg result.

The Conclusion

The figures are by no means definitive. The worst case I found shows that teams go on to win roughly 41% of the time from that position, while the other periods show the away team doing far better. I suspect that we need a far larger sample size for each result to judge definitively; however I think it’s fair to conclude that losing 2–1 away in the first leg is not a “disaster”.

Who let that gobshite on the telly?↩
Technically, this is the James M. Ross data, but I was using the RSSSF mirror as the original is no more.↩
What can I say, I enjoy that kind of thing.↩
Before you ask, no you can't have this file. The team names are not totally clean and I don't want to pass the fine work of Ross and the RSSSF off as my own.↩
Up-to and including the games played on the 31st of March, 2010.↩
I defined a draw to be a tie which is level at the end of playing time, before penalties, where no team wins on away goals. I decided to regard games which went to penalties as draws for statistical purposes as it seems improper to regard them as clear home or away wins. Feel free to disagree, good arguments may persuade me to re-think.↩

deeden

Can Barcelona come back?

The Raw Data

The Methodology

The Processed Data

The Conclusion

Champions League Post-First Leg Expectations

The Raw Data

The Methodology

The Processed Data

The Conclusion