Some people have a hard time thinking rationally when there are struggles and negative outcomes. There could be ten different things that play a part in why a player doesn’t develop, and there could be a different mix of reasons for a different player. But it’s easier to just blame the director, even if the player just isn’t very good to begin with, or if the player lacks the drive or work ethic, or if the player doesn’t like to be coached.
It reminds me of how people like to blame the hitting coach when an offense is struggling.