It reminded me of the Dierker/Holt fiasco whenever that was (2000?). I can't even remember exactly what he did, but I think he screwed up in some way that forced him to leave Holt in to face a batter when he had intended to replace him, and of course the batter clobbered him.
Dierker had mutiple mound visit fuckups. The one with Holt was with respect to the rule that a pitcher must pitch to at least one batter or record an out. There was another one where he visited Billy Wagner, then the other manager brought in a pinch hitter, but Dierk didn't wait until the new hitter was announced to go back out to the mound. The ump said it was the second visit during the same at bat, and forced Wagner from the game.