Read Sean Ingle's excellent piece on the 1985 game here.
The game last weekend went largely to form. Visiting Millwall made their vastly superior league position count, as a late goal from N'Guessan added to two first half goals to give the Lions a comfortable passage to the quarter finals. The final 3-0 scoreline, however, did little to settle the debate surrounding early kick offs in general. One season can see such games produce soporific, goal droughts (in unrelated news, Fulham entertain Stoke in next Saturday's early match), while at other times, early risers are treated to a goal feast.
If kick off time is a component of how goal laden games are likely to be, it is unlikely to be the major factor. The quality of each side greatly determines the amount of goals you are likely to see scored, with the number rising, albeit gradually, as the game becomes more lopsided. If you pitch a typical Premiership title winning team at home to a typical relegation candidate, then the chances of seeing three or more goals in the game rises well above 50%. But reverse the venue and allow home advantage to bring the sides closer together in terms of ability and the possibility of three or more game goals recedes to below 50%.
So it is desirable to include a component for team quality in any study undertaken to try to isolate factors which may influence match goal totals. I've used each team's success rate over the previous 34 games to account for team quality, together with the proportion of the day which has already elapsed at kick off time for every Premiership match played over the last five completed seasons. Typically EPL games have just greater than 2.5 goals scored on average, so a sensible choice is for two goals or less to represent low scoring matches and three goals or more for high scoring ones.
Respective pregame, team quality does provide a statistically significant indication of whether game with tend towards the higher or lower end of the scoring spectrum and confirms that more lopsided games produce more overall goals. If we now add the component of kick off time, it does appear to tweak the prediction towards earlier kick offs having slightly more goals. A noon day kick off between a typical top six side hosting a mid table team sees about 54% of games go over two goals compared to just 51% of games kicking off at 8 pm. These results are consistent with results from Omar's 5 Added Minutes blog. However, as Omar also found, the time component of the regression isn't statistically significant. The effect is very likely due to chance.
It is only when we begin to look at clean sheets and start time that we may see an effect of the widely accepted cause of differing levels of athletic capability being associated with different times of the day. Clean sheets are intimately connected to team ability and even a standard Poisson approach to expected goal rates generates a reasonable fit to reality.
If the effect is real, it is tempting to attempt to explain why it arises. Early kick offs tend to be televised proportionally more often for the domestic market, so a player may be keener to claim a late consolation goal in a losing cause to impress the watching millions. Alternatively, footballing skills have been shown to be more developed later in the day, so we may be seeing an effect that tells us something about the interplay between defensive and attacking play. Or it may just be a quirk of this sample of nearly 2,000 matches.
An athlete's daily body clock undoubtedly influences performance. The slow starting "morning" teams from the NFC West visiting a "mid afternoon" Atlanta team in the NFL playoffs, provided a graphic illustration of the wider, general struggles experienced by teams crossing multiple time zones to fight their battles. EPL teams never experience a domestic time zone premium, but two teams contesting a match where both are at their athletic peak, may produce a slightly different type of contest to one where both are nearer to their daily trough. And that difference may be picked up in the final scoreline.