Getting Traded
Banned
Is true that he didn't utilize the 3 enough, but that said, most of his teams' problems were on defense. His offenses were usually quite effective.
I remember that his philosophy was to focus on protecting the paint and giving up the 3 because it was a low percentage shot. This worked in the old days when you only had a few 3-point sharpshooters like Larry Bird or Dell Curry, but as time progressed the average NBA player became better at the shooting the 3, and despite that it stopped working, Sloan stuck to this philosophy and was getting burned a lot by it.
I haven't looked up the actual stats, so maybe someone might want to do that, and see if I'm right on this. In any case, everyone or almost everyone is shooting the 3 now and there are lots of guy shooting at 40 percent or better, which makes it a huge weapon that needs to be defended.