MySynergySports doesn't have last year's numbers and his limited playing time means he has a small sample size, but it currently ranks Asik 24th in points per possession allowed with 0.72 and 6th in post-ups with 0.52.
That being said, defense is difficult to quantify. Asik's reputation is that he is good at post-up defense, rotating on help defense, defending the pick-and-roll, and closing out on perimeter shooters. Other than that (and defensive rebounding), there's probably nothing special about his defense.
Asik didn't play that much in Chicago because he had an established, above-average veteran starter in Joakim Noah ahead of him. If you don't understand how that explains his limited minutes, there's no hope for you.