The truth behind the play-offs: late charges, relegation-form winners and 20% chaos

What determines a play-off winner: form, big-match temperament, timing your run or sheer luck? Mike Holden crunches the numbers to bring you the maths behind the climax...

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Arguably English football's greatest innovation of the past 30 years, the Football League Play-Offs remain unrivalled for drama. Barring a tweak to the away-goals rule, the format hasn’t changed since 1990 – and why would it? The conditions are perfect for ding-dong battles and those breathtaking moments that punctuate the nerve-shredding tension. Year upon year, they deliver.

But so fine are the margins between success and failure, it’s easy to buy into the notion that there’s no rhyme or reason to who goes up and who stays down. “The play-offs are a lottery”: it’s one of football’s biggest cliches and biggest myths. Yes, chance plays a significant part. But the probabilities are never equal.

Over the past 26 seasons, there have been 78 play-off campaigns, involving 312 teams, playing 390 matches. And FFT has scrutinised the data to bring you the underlying patterns that indicate why some teams have a much better chance of promotion than others.

Consider the four participating teams as A, B, C and D (from highest league position to lowest), here’s what you need to know…

80% order, 20% chaos

(Key: Team A is in the highest play-off position, D the lowest. Green: winners, amber: runners-up, red: semi-finalists)

In the early years, a school of thought developed that teams who finished highest would invariably underperform – most probably because, while the sample size remained small, each instance of Team A failing to win promotion was highlighted as an injustice compared to the way things used to be.

Promotion positions

What percentage of each play-off position gets promoted?
A: 39.7%
B: 21.8%
C: 17.9%
D: 20.5%

In fact, the opposite is true: on the whole, Team A wins promotion roughly twice as often as everybody else. In 78 campaigns, Team A has triumphed 31 times (39.7%) compared with 17, 14 and 16 promotions for the other three teams respectively. Broadly speaking, that’s a 40-20-20-20 distribution. For every five campaigns, Team A will be promoted twice, everybody else once.

The 80/20 principle is another way of framing it, whereby we might conclude that the play-offs are 80% chaos and 20% order. If we take the 40% of Team A successes, you could argue that half of them (20%) are simply the upshot of Team A being overwhelmingly superior, while the other half (20%) are the result of chance (matching the probabilities of triumph for Teams B, C and D). Good news for Brighton, Walsall and Accrington, then. 

Last-day agony for Accy, but they're in the box seat

Previous meetings count for little

Play-off results against teams beaten during the league season. Green: winners in play-off head-to-heads, red: losers

Another popular assumption is that one team has an advantage (be it psychological or tactical) over an opponent if they had the better head-to-head record during the regular season. This year, a prime example in the Championship would be the Derby-Hull semi-final: over the two league games, the Rams have won 6-0 on aggregate.

We'll beat again

How often teams repeated regular-season head-to-head wins in play-offs
Overall: 50.5%
A: 71.9%
B: 42.9%
C: 36.7%
D: 42.2%

However, the stats suggest previous results have virtually no bearing. In 188 examples where one team boasted superiority on aggregate over two league games, they replicated that success only 95 times (50.5% – pretty much a coin-toss average).

When you break that data down by team, a more revealing picture begins to emerge. Similarly to the 80/20 principle above, Team A replicates head-to-head success more than 70% of the time, whereas for everyone else that figure is consistently around 40% – in other words, they're actually more likely to lose than to win. So while Team A might be expected to repeat their triumph over the opponents they bested during the regular season, for Teams B, C and D a positive head-to-head might be considered a bad omen. Not so fast, Derby fans. 

Hull's Bruce will be pleased the Rams' 6-0 aggregate means nothing

NEXT: How important are form and big-match pedigree – and how late interlopers do well in the final