Omer Asik ain't pretty but

He's very effective on defense.

He's currently the #4 Rim Protector in the league.

FG% at Rim on starters who have played at least 10 games and defend at least 5 attempts per game LINK :

Andrew Bogut 38.5%
Roy Hibbert 38.5%
Tim Duncan 41.9%
Omer Asik 43.0%
Serge Ibaka 43.4%

He's 10th in the league in rebounding at 10.5 per game and 4th among starters in rebounds per 36 minutes behind:

Andre Drummond 14.4
Tyson Chandler 14.3
DeMarcus Cousins 14.2
Omer Asik 13.5
DeAndre Jordan 13.2

When he's on the court opposing teams score 99.8 pts per 100 possessions. When he's off the court they score 111.0. That's an 11.2 point difference. On the defensive side of the ball it's pretty clear he's elite.

Yes he's frustrating to watch, there are so many rebounds that he almost has and so many easy shots at the rim that he almost makes. If he had 10% bigger hands and 10% more explosion he could average about 3 more rebounds per game and at least 6 more points. But he's a net positive, 0.8 combined offense/defense on/off, and he's an effective defender that lets AD do his MVP thing instead of getting beat on in the post.

BTW, Robin Lopez is averaging just 7.1 rebounds in the same 27 minutes that Asik is averaging 10.5 in. He's also #19 in rim protection at 48.5% and the Blazers actually allow 1 more point per 100 possessions when Lopez is on the court vs. Asik's 11.2 points less.

To be fair Lopez' better offensive skills gives him an overall better on/off net rating of 3.5 vs. Asik's 0.8, but we need defense and rebounding from our center, not scoring. This team scores well enough, it gets into trouble when it can't get stops.