I don't like Hollins. The only reason he is an NBA player is because he's a giant human who can run faster than most other humans of his size. He has terrible hand-eye co-ordination. Stiemsma is better at basketball. I get why people like him more.
That said, maybe it's because he's hurt, or maybe he just doesn't have the lateral quickness in general, Stiemsma can't keep up with non-centers, which is a problem when playing on a defense that switches a lot like the Celtics. Hollins is impressive in his ability to keep smaller players in front of him when there's a switch, and he's really great at closing out on perimeter players who've snuck open so that they can't get off their shot, and I get why Doc prefers him. I don't think you can put Hollins out there with anyone else who isn't an option offensively, because he shouldn't be given the ball at that end of the court, even on open alley-oops. Defensively, however, he is disruptive, and not merely as a one-on-one defender against opposing centers.
But until he gets rid of his hands of stone, I will never like him. I don't think you should be allowed to be in the NBA if you can't catch a basketball.