I think CBS is hurting Sully's game the most by asking him to stand out at the three point line and space the floor instead of capitalizing more on his midrange shooting (and increased opportunities as cutter, passer, offensive rebounds and post ups due to closer proximity to basket).
I do think CBS should be encouraging Smart to drive the ball to the rim more often. I think CBS is too laid back and content with Smart taking 2/3rds of his shots from 3 point range. It is an unhealthy ratio of 3s vs 2s for a young developing player.
However, I also think vast majority of the situation is down to Smart either (1) he lacks the explosive quickness to get to basket and his offensive potential is much lower than we hope, or more optimistically, (2) he is struggling to attack quicker NBA caliber athletes / defenders and will improve over time as he better understands how best to attack those players.
Still, I do think CBS should be encouraging him more to drive the ball. To be aggressive. To make mistakes. It's the best way to learn. Smart doesn't need to drive all time but he does need to do it more frequently than he currently is.
With Olynyk, I think the biggest problem is minutes. I think players like him will struggle to be consistent from a bench role because he is a poor shot-creator. He relies on teammates to create opportunities for him. He is also predominantly an outside shooter which also leads to inconsistent scoring numbers in low minutes. So minutes are the big problem here. And Sully & Zeller are both more deserving of starting spots and big minutes so not CBS's fault.