I'm assuming it to be down to his shoulder injury, because coming to terms with it being anything other than that is not desirable.
Prior to G3 of the ECF, where he got injured, he was averaging 28/6/6 on 45/39/83 shooting on 4.2 turnovers a game. After G3, 24/8/7 on 41/43/77 with 4 turnovers a game.
The stark difference was his ability to score inside the arc. He actually shot the three incredibly well in this series, but was way off on free throws and he couldn't power through contact at all like he had been prior to the shoulder injury. I like that he took it upon himself to make more passes once he got injured, but I do think it played a huge role in his scoring difficulties.
I also think the coach failed to put the Jays in positions to succeed on offence, for the most part.