If I misunderstood your point, I'm sorry, but I will say it again, no decision should ever be made based on a 1 game result (maybe 2 for a RP'er who pitches twice in a 3 game series).
I can see, if a manager as 50-50 on the last 2 players for 1 slot remaining using the most recent sample size to "flip the coin", so to speak, but I doubt there are many exact 50-50 choices managers have to make. They watch our players all year, not just in games, but in practice, too, and they generally know who is the better choice, and no one great or bad game changes that. That's my opinion. I don't view it as a "spin."