Don't think Jeff is going anywhere! He's finally coming into his own, and there aren't many players in the league, at his height, that can do the things he can! You don't get rid of players like that.
While Rajon also had his unique skill set, there were a good 8-10 point guards in the league most would rate higher, mainly due to his inability to shoot and score. He is a wizard at passing, but really you shouldn't need 7 rpg from your point guard---so while that was great for his stats and triple doubles, shooting and scoring are way more important.
Zeller, KO, Sully, Wright, and BB give the C's a nice big man rotation!