Not defending Snit exactly, but I think the criticisms of him are outsized and misguided. For years on boards before this one, I can remember what a tactical moron Bobby was. Of course Fredi was an idiot. Fact of the matter is, every fan base since the beginning of the game has questioned the tactical decisions of their manager.
The big problem, to me, is that the performance of the bullpen has been shaky, even poor, in high leverage spots. You can point to Luke with a 2.00 ERA, but I promise you, those few runs he allowed were in high leverage situations. Last year, Minter, Greene, and Martin were money (lucky money, their babips and xwOBA against would suggest). This year, Minter's recent recovery notwithstanding, they've been awful. That's not even getting into his $13M man's gopher problem.
Snit may not be pushing the right buttons at the right time, but even if he was, the pen is not performing well. I put the thrust of the problem on that.