A season's fate decided outside the season itself
In a straightforward system of automatic promotion and relegation, a club's league position at the final whistle of the last regular fixture settles its fate immediately and completely. A play-off structure changes that by inserting an additional, separate contest between a club finishing near the bottom of one division and a club finishing near the top of the division below, meaning a club's ultimate fate is decided by a fixture that exists entirely outside the regular league table it spent the whole season compiling.
This produces a distinctive kind of tension unlike anything else in the regular season. A club that performed well enough across many months to avoid automatic relegation can still be relegated by two matches against a single opponent who was, by definition, not quite good enough for automatic promotion either, a genuinely different sporting test layered on top of the league campaign that produced the opportunity for it in the first place.
Different qualities, different pressure
A play-off tie rewards a somewhat different skill set than a long league campaign does. Consistency across many months, the quality most responsible for a strong league finish, matters far less across a two-legged play-off than composure under acute, immediate pressure and the ability to manage a shorter, higher-stakes occasion. Clubs that were unconvincing for large stretches of their regular season sometimes perform excellently in a play-off precisely because the format rewards a different, more compressed kind of resilience.
This mismatch between what earns a play-off place and what wins it is part of why the format generates such strong reactions. Supporters of a club that dominated the regular season standings but stumbled in the subsequent play-off often feel, with some justification, that the format has undone months of genuine achievement through a comparatively small sample of matches against a single opponent.
Why the debate has no easy resolution
Defenders of the play-off format argue precisely the opposite case: that a small sample of high-stakes matches provides a legitimate and exciting additional test, rewarding composure under pressure as a genuinely valuable footballing quality in its own right, and generating a dramatic occasion that a straightforward automatic swap between divisions simply would not produce. Broadcasters and neutral observers, for their part, tend to appreciate the additional drama the format guarantees at the end of an otherwise settled season.
Both sides of this argument have genuine merit, which is part of why the debate persists without resolving cleanly in either direction. The play-off format is best understood not as an obviously correct or incorrect structural choice, but as a deliberate trade-off between rewarding consistency and rewarding a specific, concentrated kind of pressure performance, a trade-off different footballing cultures have been willing to make differently.