I've always thought it was executed really well. Burnham sensed that something was off about the ship right from the start, and as we slowly got to know the crew members she interacted with, it slowly became apparent that the crew was just as idealistic as anyone else in Starfleet - the problem was Mirror Lorca all along. Combined with the stress of the war, he pushed everyone over the edge. He wanted to get home, no matter the cost. If I had him constantly breathing down my neck and broadcasting crying children over the PA system to guilt-trip me into working harder, I would've lashed out at anyone in the general vicinity too. It wasn't lost on me how the atmosphere of the ship instantly became a million times less suffocating after they rooted him out.