I think another factor to consider is that the overall "quality" of most of so-called fringe players on the roster generally leaves a lot to be desired. I doubt that Rocco has a large say on the composition of the roster he has to work with from game to game and that means that the replacement for that situation is oftentimes less than optimal.
I view it more as he's throwing things up against the wall, in the hopes that something will stick, because he doesn't have very good options available to him most of the time. To me, that's primarily a fault of the ownership and front office and not directly him.
You can only play with what you have and Rocco oftentimes doesn't have much quality to play with. I think that has a lot to do with the continued Margot pinch hitting opportunities, among other things.
While a valid concern, the lack of trust he appears to sometimes have with his younger players is a different story line to be debated separately.