You're not in the minority. I don't mind Postma's "game," but at 8-10 minutes a night, it won't improve. Same goes for O'Gara. To be honest, I don't like the idea of O'Gara getting low minutes when he can get more than double in Providence.
Well, in my opinion that is exactly what O'Gara needs. Low ice-time in Boston rather than high-minutes in the AHL.
There really isn't much for O'Gara to learn in the AHL at this point, he's on a much higher-level than most players in that league. He could benefit from bottom-pairing minutes with an NHL team for sure. He's ready for the show, if you ask me.
O'Gara will most-likely never be a high-caliber two-way defensemen due to his limited offensive capabilities, but he offers a steady, puck-moving game as a large defender. You don't notice him much, and that's a good thing.
I will say this though, there just aren't many other 6'4" defensemen in the NHL that can skate as well as he can. He has a powerful, yet silky-smooth stride that you just don't find in players his size. O'Gara with the right amount of seasoning in Boston, could be a quality defensemen for the teams 2nd-3rd pairing.
As far as Gryzelcyk goes, I think a lot of people forget that he was a true rookie last year in the AHL for Providence. He still has room to grow and I think he's an NHL player. Is he a prolific top-4 D? No, but he's a good puck-moving defender who can make some really nice plays on the blueline. There have been several occasions in Providence this year where he pulled his best "Kaberle" impression with an impressive keep on the offensive blueline. He's not big, but he's a very fast player, which makes up for some size disadvantages.
Gryzelcyk has great vision and defensive awareness too, so when he gets to the puck in his own zone, he battles hard to retrieve it. Moving the puck out of his zone quickly is what makes him a good player to be called up.
One of the comments here said Gryzelcyk should only be called up in the event of an injury and I strongly disagree. The Bruins may not have the roster space for him so it may not be for another year or two, but Gryzelcyk is an NHL player. I think there are plenty of teams in the NHL that could directly benefit from having him on their 3rd-pair right now. Maybe his real NHL opportunity will end up being as a result of a trade or signing elsewhere when his contract is up, but he is a quality defender and will someday be an NHL regular.