Good defender + very good penetrator (mainly off pick and rolls where he uses his size very well) ... poor-to-very poor at everything else.
Lack of scoring ability -- no perimeter shot, no midrange shot, poor finisher in the paint, doesn't draw fouls -- a weak scorer in every sense.
Lack of point guard skills -- very poor passer relative to his position, only useful passes are on the drive and kick and even then those passes are weak, so-so handle, poor decision making, can't run an offense -- overall a horribly inefficient offensive player. Only effective when he has the ball in his hands and allowed to dominate the ball and ostracize his teammates. Also, a below par rebounder despite his impressive size/athleticism.
Roko Ukic is 26 years old at the end of this season and has reportedly shown little improvement over the last few years. Considering his age + lack of improvement + clear need for improvement ... it doesn't look like Roko will ever become good enough to be a rotation worthy player in the NBA.
I don't Ukic is currently good enough to be in the NBA. He's a very poor third string point guard. Capable of a great game here and there but a dozen bad games usually follow. He does a lot of harm to his own team due to his offensive limitations.
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In terms of trades, I think a team could probably pick up Ukic for a second round pick.
I think Lestor Hudson is a better prospect though. I'd rather keep Hudson than make a move for Ukic.