What’s an away goal worth? An analysis of ten years of Europa League and Champions League football.

Andriy Shevchenko, Dinamo Kiev, August 17, 2010: “…in the first match at home we have to keep a clean sheet, but the most important objective is to score.”

To score or not to concede? That is in fact the questions posed to all teams competing in this week’s first leg of the all important play-off matches for the lucrative group stages of the Champions League and the Europa League.

There’s this wide-spread knowledge that scoring away from home is a big step towards winning a tie played over two matches. This article on 11tegen11 is attempt to quantify to value of the first leg’s result. In other words, how many teams did qualify for the next round of knockout football given a certain first leg result.

The database used for this analysis was composed of data by Bert Kassies. It includes all knockout matches played for the Europa League and Champions League. Group stage matches were excluded. A total of 1926 matches were included for analysis. Results are presented as wins, in which case the team playing the first leg at home won the knockout match, as losses, in which case the team playing the first leg away from home won the knockout match, or as penalties.

Let’s take a 0-0 score as an example of how to interpret this table. It says that after a 0-0 score, the team that played the first leg at home won 70 (36%) of the knockout rounds. 118 (60%) were won by the team that played the first leg away from home and 8 (4%) ended up in penalties.

From this table we might draw a line were an away team succeeds in winning over 50% of the confrontations. As expected, the team that wins the first leg of a knockout match has the biggest chance of winning the match, however at 2-1 (55%) and 3-2 (53%), this advantage approaches the 50% mark.

From this table it is further able to assess the value of pursuing an extra goal or the concentrate on not conceding. Let’s take the late 3-1 goal scored by Pazzini for Sampdoria away at Werder Bremen last night. This made Sampdoria shift from a 2 out of 92 (2%) perspective to a 12 out of 82 (15%) perspective.

While this table might not be perfect science and historical results do not present any form of prediction for the future, it does indicate how teams in a comparable situation have fared given the first leg result in a European Football knockout match.

HOME absolute relative wins losses penalties wins losses penalties 0-0 70 118 8 36% 60% 4% 1-0 143 72 12 63% 32% 5% 2-0 116 10 5 89% 8% 4% 3-0 90 2 1 97% 2% 1% 4-0 52 100% 5-0 26 100% 6-0 11 100% 7-0 1 100% 8-0 2 100% 0-1 22 138 7 13% 83% 4% 1-1 62 133 10 30% 65% 5% 2-1 74 56 5 55% 41% 4% 3-1 70 12 85% 15% 4-1 25 2 1 89% 7% 4% 5-1 11 100% 6-1 5 100% 7-1 8-1 2 100% 0-2 2 89 1 2% 97% 1% 1-2 7 96 7% 93% 2-2 15 67 18% 82% 3-2 20 17 1 53% 45% 3% 4-2 7 3 70% 30% 5-2 5 100% 6-2 2 100% 7-2 1 100% 0-3 52 1 98% 2% 1-3 49 100% 2-3 2 26 7% 93% 3-3 2 7 22% 78% 4-3 3 1 75% 25% 5-3 2 100% 6-3 1 100% 0-4 21 100% 1-4 17 100% 2-4 6 100% 3-4 5 100% 4-4 1 100% 0-5 10 100% 1-5 8 100% 2-5 1 100% 0-6 2 100% 0-7 1 100% 0-8 1 100%