I'd like to go on record as saying i'm a lowry fan, but as my dude Matt here mentioned, he's had that "breakout star!" label for a while now. Not to mention he's clashed with every single coach he's been with. Granted, Casey is possibly retarded, but it is a questionable trait. Was he used properly? Not really. Should he have been that ineffective, especially on defense though? No. That's what concerns me about him the most. When everything's going fine he's great but when stuff happens its like he shuts down completely.
That's why i'd look long and hard at getting a new PG like Bledsoe.