I don't think the idea the manager should be insulated from criticism stands up to any analysis.
First, there's no proof I'm aware of that Falvine are making in game decisions. And in fact, I'd bet a large sum of cash they aren't.
Second, that Rocco is implementing an overall strategy with regards to pitching decisions is plausible, even likely. But even within that framework, individual, game level decisions are on Rocco. Is it your contention Falvine are calling down to the dugout during games and telling Rocco who should be on the mound, and when? Does Rocco consult the FO when decisions are made to warm up reliever(s)?
I think the opposite. That's Rocco and his pitching coach.
And third, there are PLENTY of other reasons someone could question the manager. Playing time, lack of fundamentals, plays put on, not put on. Infield in, or not. Sacrificing. Batting order. You name it.
If you like Rocco, fine. You have every right. But stick to why.
Jumping on others, for holding the manager responsible for managerial decisions, isn't a valid argument.