I would say move Zupp to SG and Swap robinson SF... The main thing I see in SG is SPD and with Robinson his lack of Speed makes him a foul liability where against a SF his high ATH will help him out as you don't always see Fast PER shooting SF's. The other thing is I would find a way to get Ratko out of the starting lineup. He has too low of DEF for me to consider him a starter. If he has the potential to get over 50 playing him works as 50 DEF is my bare minimum at D2 Starters, however if he is a solid 38 for DEF its very easy to exploit him.
Overall you have 2 DEF problems 1 is easily fixed with robinson and then Ratko I'd even consider dropping Williams to SF and Robinson to PF so you have to worry less about the SPD issue. I really like where Headley is, if he has any sort of potential in ATH I would put him in and 20 practice minutes in Physical then take Ratko out. This would even out your DEF holes that I see and stabilize. Lastly I agree with Skinndogg that a 3 point threat is necessary, it would help as I bet a lot of the teams you have are running - defense setups which hurts your ability to rebound and also make you 2 dimensional.