He mentioned that Sid was one of the reasons he came, to coach that high potential kind of player. But that's neither here nor there.
I think Sid is more aggressive than he's appeared. You can see it when he flies back on D for a big transition block. He know how to use his athleticism in that scenario.
Given that, I think a bit of what we're seeing is uncertainty. He doesn't know what the hell he's doing (a significant problem). Ergo, he looks tentative. Also, he's so smooth, that he looks effortless at times, almost lackadaisical. Lamb and Rudy had the same problem, with people calling them lazy.
Sid's biggest problem, in reading between the lines, seems to be work habits. He needs to get better their full stop. Everything flows from that.