Coaches are interchangeable in the NFL, too

2012 Fired NFL coaches

Firing these guys probably didn’t change anything


Add football to the list of sports where coaches appear to be interchangeable. Brian Burke has written a post where he argues that randomness and player performance explain the vast majority of the variation in team performance. This means that other factors — including coaching — don’t have much of an impact on team performance:

There are exceptions, like [Mike Singletary], but my hunch is that NFL coaches are mostly interchangeable.

I think at the NFL level, all coaches employ the same best practices. There is no secret sauce that one coach has over another in terms of instruction, motivation, strategy, etc. This is because of the highly mobile, fluid market for coaches and the large size of their staffs. There are very strong constraints on deviation from league norms in any dimension.

Also, from statistical analysis, we can measure the variance in team performance attributable to randomness (sample error due to a short 16-game season) and player impacts (the addition or subtraction of a player’s impact on team production, player interaction effects). There is very little variance left that can be attributed to other causes, including coaching. In other words NFL outcomes are overwhelmingly driven by player talent and luck, and there’s not much room left for coaching to make a big impact.

This is similar to the argument Dave Berri has made in the past about coaches in the NBA. JC Bradbury has made the same observation about MLB managers. And we’ve seen equivalent research on NHL coaches and soccer managers.

But it’s important to note what the research doesn’t say — none of the research says that teams would be better off without these coaches and managers. Here’s what Dave wrote about the interchangeable nature of coaches for Freakonomics a year ago:

What does all this mean?  Henry Abbott – of ESPN’s TrueHoop – suggested in 2008 that the argument that NBA coaches don’t tend to change player productivity indicated that coaches could be replaced with “deck chairs.”  These studies, though, don’t indicate that teams are better off without a coach. That is because none of these studies looked at a team with and without a coach. What these studies did is look at teams or players with different coaches and failed to find much of a difference. That suggests that coaches in sports are not very different from each other. It may be true (and more than likely very true) that you are better off with a professional coach than with a random person grabbed from the stands (or no one at all). But it doesn’t appear that the choice of professional coach matters much.

Such an argument echoes something that was noted by Adam Smith in 1776. In An Inquiry into the Nature and Causes of the Wealth of Nations, Smith argued that the daily operations of a firm are run by “principal clerks” and such clerks are essentially homogenous. Or as Smith put it: “their labour of inspection and direction may be either altogether or very nearly the same.”

Smith’s view of those charged with the “labour of inspection and direction” certainly runs counter to the view people have of coaches and managers in professional sports. But the sports data appears to be consistent with Smith’s view, even if he wasn’t explicitly talking about sports.

So why do principle clerks and coaches appear to be the same? Essentially, coaches appear to receive similar training, face similar information sets, and ultimately make similar decisions. The results – perhaps not surprising when you consider these similarities – are that outcomes with different coaches are quite similar.

Incidentally, this phenomenon goes beyond coaches and managers: Dave Berri and Stacey Brook have noted the interchangeability of NHL goalies as well.

Remember this the next time you are tempted to call for your favourite team to fire its coach!

– Devin

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