Unless either player wants to sign an extremely team friendly deal, I see no reason to do anything now. Zeller looks like he could play himself out of the rotation and Sullinger hasn't proven he's worthy of a long term commitment yet. With Zeller, I think there's a good chance his value may actually decrease by this summer, so I'd definitely hold out. With Sully, it could go the other way, but I'd rather pay more later and be sure he's worthy of it than gamble now on a long term deal and then see him continue to do what he's done up to this point.