Oesterle is pretty good with the puck and in transition. He has an active stick and breaks up alot of plays. I notice him defending a lot in the neutral zone in a good way. It's when the other team establishes position that he gets exposed. He doesn't really have the size and reach to be effective, and like most bottom -pairing defensemen makes bad reads.
Like Guest said, if you want your lower-pairing D to move the puck, it's always at the expense of their defense (otherwise they would be top-pairing D).
I would guess they already have made a decision on his future with the team. Wouldn't be surprised if they kept him because they talk about so transition in general so much, they clearly value that part of his game. On the other hand, he's an expiring contract, and there is always a market for depth defensemen at the deadline. SOoo...