Problem is you mentioned Sid. He's not good at guarding anyone right now hence why he doesn't play. He wanders looking to block a shot and hasn't done that well either. For now, at least for me no matter what, Polley would be my guy ahead of him even guarding a 6'5" guy because at least he can score.
I'm envisioning Akok in that spot as the 6'5" guy plays the 4 for Buffalo. I did concede I'd play Polley as a backup 4 if I were Hurley (10-12 minutes). I'm sure I'd play him 5-10 minutes at the 3 as well (more if Buffalo goes zone at all), but also a few minutes each of Sid and Adams (Adams would get more minutes as the backup 2), and then the other 20-25 of the minutes at the 3 to Bouknight. Sid can hit the offensive glass from the 3 at least, which is taking advantage of the opponent's mismatch (he's been our 2nd best offensive rebounder to this point). But still, I'd only give him 5-10 minutes total unless there's foul trouble.
And again, that's just for this particular matchup.