Perk was heavy and wide and took up space what I call the BIG BABY effect ...using size to protect the rim.
Streamer actually plays basketball , can jump , run and shoot
I think that's really underrating Perk's contributions. Perk's defensive ability wasn't just because he was strong; if it was, teams would simply hire sumo wrestlers to defend the paint. Instead, he was strong, had good defensive instincts, knew when to rotate, and knew when to stay home. He was good at both one-on-one and team defense. He was also a pretty good rebounder, a great outlet passer, and a very good screen setter. His contributions on offense were under-appreciated, as well, in my opinion; it's not easy to average 10 ppg as a 5th option, but Perk did so.
Stiemsma has been solid for a guy who came into camp with no expectations, but it's hard in my mind to put him ahead of a championship-level player like Perk.