Moqui's point is accurate and valid. Are you saying my previous example is not? Since you never acknowledged it, I'll reiterate, in case you missed or ignored it. As a freshman, Christmas played much better when Melo was suspended and he wasn't looking over his shoulder. I know there are other examples, this a quick one off of the top of my head.
Obviously JB plays the guys that have proven themselves. He also yanks some guys instantly after they make one mistake while letting others play through theirs. You can see that some of the guys that are routinely yanked quickly play tentatively and look over their shoulders. There's no way to know whether BJ would work out his jitters and play better if he was given a few more consecutive minutes because it's not going to happen. Even if he did, people would just say he must be practicing better and that's why he's getting more playing time. Of course this may be valid too. I don't think either one exists in a vacuum. Guys that get more court time feel better in games. Practicing against your teammates that you're already familiar with at less than game speed absent the crowds that accompany a game alone will not prepare you for a game atmosphere the way the game minutes will.
If he has been truly practicing that bad, he should've never seen the court so that a redshirt would be in play. We all know his age and build would've justified it. Why play a guy one minute in a game? It's not enough for him to learn anything. It's not enough to really see how well he's going to play. And it's not enough for him to give anyone a real break.