Quantifying the effect of coaching can be incredibly difficult and at least in my opinion it’s far more nuanced than the win-loss records that often serve as the final word in evaluating coaching quality.
Much of what a coach does isn’t seen by fans simply watching a game. The countless hours spent watching film and preparing strategy aren’t shown on ESPN and even when the lights are on viewers aren’t privy to every decision and play call directed by the head coach.
One thing that everyone sees and is almost always criticized by fans and broadcasters alike is the strategy related to calling timeouts.