The argument that using player X is wrong because you held back player Y and he didn't end up impacting the game is some remedial Logic 101 bullshit. Come the fuck on. You don't know whether Player Y will impact the game or not when you decide to use player X, but you do know that Player Y may be needed to do any number of things, whereas Player X is pretty much only good for the one thing you are having him do. The marginal utility of burning Y over X for a fairly menial task is quite a bit lower than the downside of, say, having to use an emergency catcher, or running out of pitchers.