For decades a two-legged tie level on aggregate was decided by which team had scored more away from home. The rule was removed because the problem it solved had largely disappeared.
The rule addressed a real disadvantage
When the tiebreaker was introduced, travelling to an away fixture meant long journeys, unfamiliar and often poor pitches, and hostile conditions that visiting teams struggled with.
Away teams defended deep and settled for narrow defeats, which produced cautious first legs and killed the entertainment value of the tie.
Counting away goals double gave the visiting side a reason to attack, since a single goal carried value beyond the scoreline itself. It rewarded ambition in the match where ambition was scarcest.
The conditions it corrected have changed
Travel is now short and comfortable, pitches are consistent across the continent, and preparation facilities differ far less between clubs than they once did.
Home advantage has narrowed accordingly, so the compensation the rule provided is applied to a disadvantage that is much smaller than before.
What remains is the distortion, since the rule now hands an advantage rather than restoring a balance. A correction applied after the problem has gone becomes a distortion.
The tie became asymmetric in extra time
The clearest problem appeared when a tie reached extra time. The team playing at home had thirty additional minutes in which to concede a goal counting double.
Its opponent had the same period in which to score one, so the away side gained an extra opportunity the home side never received.
Coaches recognised this and managed the second leg around it, which produced conservative football in exactly the period meant to be decisive. The home crowd watched its team defend the additional half hour.
Behaviour reversed over time
Teams playing at home in the first leg began protecting their goal rather than attacking, since conceding was doubly costly.
The rule intended to encourage attacking football was therefore discouraging it, at least in one of the two matches. Opening legs grew steadily more cautious as coaches understood the arithmetic.
Removing it means both legs are worth the same, and a tie level after two matches is settled by extra time and penalties.
The change altered how ties are managed
Without the tiebreaker, a first-leg away draw is no longer a strategic result and there is less reason to sit deep in the opening match.
Teams trailing in a second leg can no longer rely on a single away goal transforming the tie, so the endgame is simpler and more direct.
Extra time now decides more ties, which lengthens matches but resolves them on the pitch rather than on an arithmetic rule.
