I would replace Greggio with a higher quality, younger big man. Somebody with IS/ID/RB/SB around 11/13/11/9, no older than 27, so he can carry your team for the next few seasons. You should increase your depth, too, probably with a quality backup SF.
Your arena is fine, I think you actually need to put more cash into players, since you aren't selling out, and you'll be over 15k seats once your expansion finishes, that'll be ok until you hit D2.