Callahan: As solid and sturdy a two-way defender as you'll find with good hands, mobility and IQ for the defensive side of the game. He doesn't "wow" you with the puck on his stick, but shoot for purpose of tips and redirections from the point, usually in the way of an accurate, well-timed wrister.
He's a high-character type of guy and joke all you want, but you really can't have too many of those guys in the system. How else do you think the Bruins attract other potential UFAs and NCAA guys looking to sign somewhere? I'm not sure he's got top-four potential, but I think he could be a bottom-pair anchor that you don't worry about and need to replace for a few years should he make it.
There's a lot to like about the way he carries himself on and off the ice, and being in Providence frequently, I can see why they'd trade a low-value asset to get the inside track on getting him under a contract here.
Callahan right now is a better prospect than what your average seventh-round pick will be, so I have no issues with this move and rather I appreciate them identifying, targeting and acquiring someone they like enough to move an asset for in this fashion.