Extra Time and the Away Goals Rule
I recently questioned the relevance of the away goals rule in normal time, and received a few responses that suggested the rule was particularly unfair in extra time as it gave the visiting team an extra half hour to find an away goal.
There’s a counterargument to this; that the rule balances out home advantage. This second leg home advantage is also often arbitrarily assigned in the later rounds of European competition.
Since the away goals rule was introduced to European football in the 1960s, the European Cup and UEFA Cup (and their more recent versions) have had 198 games enter extra time in two-legged, non-qualifying rounds. This sample excludes matches under the golden or silver goals rules.
The results are broken down as follows:
Of matches that didn’t go to penalties, marginally more resulted in the home team advancing to the next round, but this difference is insignificant even before accounting for differing team strengths* through the potential effects of seedings.
Although a very small sample of matches, the away goals rule has historically eroded virtually all of the advantage gained by playing the extra 30 minutes at home, without tipping the balance the other way.
Ideally, we’d have a larger sample of games from more recent years to remove any effects of home advantage over time.
The away goals rule seems to serve a strong purpose in extra time; its relevance during the 90 minutes is perhaps more open for debate.
*Team strengths were proxied by the respective clubs’ Elo rating at the time, from the excellent clubelo.com.