Callis constantly does stuff like this. It's part of the BA standard operating procedure - they like kids who haven't played long enough to struggle and almost everyone struggles at some point. Once they do struggle then the next untested kid moves to the front of the line. A year ago he'd have probably listed Delmon Young in front of all of them.
As for the Uptons and Bruce, I figure all three will be kicking tail and taking names. Who'll be the best megasuperstar? Why even pretend like you know? Any random order will do.
The thing B.J. has going for him is OB. That .390 mark in the minors is pretty heady stuff. Neither Bruce nor Little Upton has been able to match it.