Ullmark visibly injured and unable to move laterally in games 4 through 6 and he leaves him out there to dry, then switches to an ice cold Swayman who hadn't played a game in 2 1/2 weeks for the do or die game 7.
Hall, Coyle, and Debrusk carrying the offense through four games, then reinserting an injured Bergeron and Krejci back into the lineup and reducing the ice time of the aforementioned. Also not being able to make up his mind and shuffling Bertuzzi and Debrusk between lines 1 and 3 the last few games.
Grzelcyk getting blamed for Ullmark's turnover in game 5 then getting scratched for Clifton, who got thoroughly abused by the Panthers in game 6. Taking McAvoy away from Gryz, his regular partner all year long and putting Orlov with him having not played together before. Forbort being put into the lineup after a month off.
It was a series of bad decisions, but the worst was the lack of accountability that he showed in every interview during and after the series. He lost me then and there.