You're overthinking this. After a made basket, JGIII sets up somewhere around top of the key in the backcourt. When they roll the ball in, all he has to do is move towards where the ball is rolling. As soon as they opposing player picks it up, he falls back into his position. That's it. It's just to force them to use clock. He's not defending in the backcourt, just making them pick it up. And there's a good chance he's back on D at the same time the guy who inbounded the ball gets into the halfcourt. I think some people forget that the inbounded also has to run upcourt. He doesn't teleport into position. Also keep in mind, i'm only espousing this strategy in situations like the other night when we have a sizable lead with under a minute.