I don't know much about O'Brien, as I have never paid much attention to other teams' coaches, but so far it seems to me that he's a very hands-on coach as far as personnel decisions go.
Last summer, when TPTB were making moves like the Harrington deal, and Cro for Quis, all you heard was Donnie Walsh talking, with a little bit of Bird. If Carlisle was asked about personnel moves, he would answer, "He's a good player, we'll see what Donnie does" (that's paraphrased).
This year, we're hearing Larry with a little from JOB. But what we're hearing from Larry is, "We went and got this guy because he fits in with what Coach O'Brien wants to do."
It's something I really like because who knows better than the coach when it comes to what kind of players the team needs. The coach best understands his own style. The coach best understands the team's needs.
Is this a O'Brien trend, or is it a Bird thing? Or, a combination of the two? Either way, I like this approach to player signings and management.