Yes and no.
Yes in the sense that it seemed nobody was able to play football last year. There's only so much that can be explained away by bad form or even bad morale in the team. Several players were sort of given a pass because of recent injuries but honestly as I said before nobody besides Danilo (perhaps Kostic) was good all the way through the season. They failed as a team but also as individuals. No question.
But also we know from earlier years that Chiesa is a monster of a player. We know from earlier years that Di María is a monster of a player. We know from earlier years that Vlahovic is a monster of a player. The fact that all three played nearly exclusively like shit, and that none of the three is comfortable in the 'system' we saw last season lays the majority of the blame on Allegri imo.
Why on earth would you try to fit square pegs in round holes all fucking season without tweaking the formula? Play to maximise the stellar talents of your key players, not play in a way that looks like a deliberate attempt to minimise them.
I'm gonna pull a Vlad here and suggest that if we'd had a coach that thought that way around we'd have seen all three play much much better football. And that's where you get your morale, which breeds good form.