I feel Fraschilla's assessment is spot on.
The C's should package a player or two, plus their pick and move up, and see if they can't steal him from a team that already has a front line center. Or possibly throw in another 1st rounder from 2016.
I'm not sure the Celtics will be in contention to acquire a solid center in the 2015 free agency, seems like many of the big guy's are staying home.
I don't think it's spot on from the offensive side. WCS has no offensive game other than at the rim. His TS% is likely to suffer a bit in the pros and having more space to operate in isn't his issue offensively. OTOH, he is playing close enough to the hole to get lobs in a PnR and runs the floor well enough to not be a complete zero like some D big men.
Defensively, he looks to be elite and should be outstanding against the PnR with his ability to recover. Blocks are very over-rated, but there are legitimate questions about his rebounding that appear to be unanswerable due to the way he was utilized defensively. There's a split on WCS and I'm not sure about him either. We need a rim protector, but we need more offense as well. Not sure Turner is not a better choice if his legs are OK given the lesser cost to move up.
Secondly, we have assets to trade up with someone like SAC at 6 who's dying for a PF and/or SG, our picks this year are worth more than theirs (according to Tankathon's power rating), and they don't need a center.
http://www.tankathon.com/power_rankings