My Scouting Report (FWIW)
Olynyk has the "potential" to evolve himself into a better than average starting center. From what I understand, he was a PG in high school but then sprouted up. He needs to be able to play only a little bit more physically and I think he could defend centers and rebound sufficiently. The physicality can come from better overall conditioning; I don't think he needs to bulk up necessarily; wiry strong is OK too. If he can get to the point where def/reb is serviceable, he will be productive because he is a tough match up on the other end. No, he is not a "rim protector" but I think the perceived value of that become overstated. Just defend your man and contribute to team defense is sufficient.
Faverani looked good at times and not so good at times last year. I am still not sure which version of him is the real Fav. I see him more as a capable back up, which is OK. A capable back up is better than a bad back up.
Zeller is a TBD for me; I have not seen him play enough to have formed an opinion. In spite of not really having anything to base my opinion on, I find myself being optimistic that he can be a serviceable starting center in the couple of years time frame.