First of all, I'm not against McBee playing. He has a role. He knows his role. He rarely, if ever, tries to exceed his role. He is, statistically, the best shooter on the team right now.
However, considering the parameters you listed for playing McBee, why is Kenny Hall playing so much? If you insert Hall's name everywhere in your post where McBee's name is now, it would seem to be the counterpoint to your idea that the best players play because, "they earned the time with hard work and effort". It seems the only thing keeping Hall from playing more is his inability to play without fouling, when in fact, he should be riding the bench in favor of Miller, who as we saw last game, plays with more desire, purpose, and hustle.
It's just a thought and I have no problems with your logic and reasoning for playing McBee. In fact, I agree with it. It just seems like that logic should carry over to all players, though in Hall's case, it doesn't seem to apply.