I couldn't argue with the result, but I surely wouldn't hire someone as GM based on such a decision, as it was chance alone that saved the decision from being horrendous.
Similarly, if I offered you 10 dollars for your house, you'd be stupid to take the deal. But if you used the 10 dollars on a lottery ticket and won, you'd be a genius? I don't see how that makes sense.
Championships does make everything better, but does it not matter if, for example, the player you traded for contributed nothing to the victory? You still won, and that's the bottom line, but if you were offered to reverse the deal, you'd likely still take the pick back. At least that's in line with the result-oriented evaluation of individual actions.