Both Zeller and Sully are good buy low options for a franchise that has little to lose by signing them. While Zeller is a fringe NBA player due to his weaknesses, he adds a veteran presence to a team that has no depth at the PF/C position. Looking at BKN's roster, the starting C is Mozgov, with his only backup being a rookie in Jarrett Allen. Their starting PF is Booker, with Quincy Acy as a backup (ESPN has him listed as a SF?). Lack of depth at C/PF was a huge problem last season.
Zeller may be a decent fit given that Atkinson likes to play uptempo, and we all know that Zeller is very good at running the floor. Sully could certainly help Brooklyn coming off the bench. He would have been a far better option than Justin Hamilton last year.
Brooklyn will still be horrible, but again these are low risk moves for a team that doesn't have its pick once again this year.