Certainly there are human elements that have to be taken into account, but human beings are inherently terrible at understanding cause and effect and seeing patterns that aren't there, and ex post facto analysis of coaching decisions that take into account whether those decisions worked out or not aren't particularly useful.
For instance, not pinch hitting for Chris Carpenter in this game when he lead off the top of the 8th is an objectively bad decision that was justified at that time using much the same logic as the decision to leave Pedro Martinez in this game, which was also a bad decision. Grady Little isn't a worse manager than Tony LaRussa because his bad decision didn't work out, and LaRussa isn't better because his bad decision did work.
In the broadest sense, results don't matter. The goal is to make the best decision you can every time you have to make a decision, and let the results come as they may. In the long run, that's how you win.