All these years, we have been assuming that coaches were too conservative in benching starters with foul trouble. If you're scared they'd be kept off the floor, what's the wisdom in keeping them off the floor?
Researchers have dug into this question, and found something surprising: The reason to take starters off the floor with foul trouble is because when they're playing with lots of fouls, they don't play as well.
"Our analysis shows that a starter in foul trouble should be yanked from the game," write Allan Maymin, Philip Maymin and Eugene Shen. "If left in the game, the player may become a liability, since he is afraid of picking up another foul."
I wonder if coaching could help that. If you just told your players to play their brains out, fouls be damned, you might moderate the effect the researchers discovered. (They also found evidence that Don Nelson apparently did something like what I'm describing. He was a major outlier, bless his unconventional self.)
Kevin Pelton discusses the research on Basketball Prospectus and concludes:
It would be a mistake to read too much into this latest study. It generally seems to suggest that coaches should not be particularly worried about foul trouble in the first and second quarters, except to the extent that it produces subsequent second-half foul trouble. It also operates under the rule of thumb that foul “trouble” exists only when a player has more fouls than the current quarter, so coaches who bench starters who pick up their second foul in the second quarter are still being overly conservative by this heuristic. Lastly, this kind of study is too general to apply to every situation. It’s much more sensible to bench a marginal starter than the team’s star player. Still, these results provide an interesting new perspective on how coaches should respond to foul trouble.