Are NBA Coaches Too Conservative with Players in Foul Trouble?

Coaches in the National Basketball Association (NBA) typically bench players who are perceived to be in danger of fouling out. I examine the efficacy of this strategy. At a baseline level, it seems dubious to guarantee that a player misses playing time for fear that he might miss time later in the game. However, there are broadly two categories of reasons that coaching conventional wisdom might be optimal. First, it is possible that players who are in foul trouble tend to play poorly, and thereby hinder their team's performance. And second, the end of the game might be meaningfully different from the rest of the game, such that having the team's best players available for the final minutes is more valuable. Section 1 demonstrates that benching players in foul trouble does not merely shift the minutes that players would typically rest, but instead decreases their overall playing time. Section 2 reveals that having a player on the court in foul trouble actually improves team performance. And Section 3 provides evidence showing that the play at the end of games does not justify the decrease in playing time that accompanies benching foul-troubled players. Taken together, this analysis demonstrates that in general, coaches should not bench their players because of foul trouble.