Well, yeah, if players don't play well, then the decisions the manager makes don't work out.
I don't think the bullpen game was some "master class" move, but it essentially worked out the way Murphy intended it. Only allowed three runs total, got the relievers work, and won the game.
I try not to be a "results-oriented" thinker (though I certainly stray a lot). I don't see Ashby's struggles as a failure in managerial strategy - he just had a rough couple innings. There was no reason to expect he'd be bad, as he's been fantastic all year and just pitched great the other day. The bullpen game was fantastic the rest of the way and pitcher usage likely wasn't much different than it would have been had Ashby pitched well. So instead of spreading three runs across nine innings, it was three runs in one inning (yes, I understand that scoring in bulk early can change psyche and strategy).
And hell, had the ump been decent, Ashby probably doesn't walk the guy in the first inning and gets out of there unscathed.
The part I question about the pitching decision was that had Priester pitched, he'd then be available to start Game 5 on regular rest. But now hopefully we won't need that.