You can't tell much from OTAs, so it makes sense to hold off on the QB decision, as annoying as it is. But I'm appreciating why at some point you need to know who you're going with and tweak the offense accordingly. If you have three starting QBs in August, then you kinda have none.
Ed Bouchette's latest column: http://www.post-gazette.com/pg/10143/1060189-66.stm
As far as a guy who's in the backfield strictly to block... well, this is one of those things where it's a tool that can be used, but I see no need to insist. Some squads are set up well to make it work and some aren't - I guess my bias is actually to have people who can both carry the ball and block line up at FB. Just personally partial to multi-back sets where everyone's a threat.