Really, really, good
I compared the 29 centers (position 4.5+) seeing at least 1,500 minutes of floor time this season, based on their own and their matchup's mano-a-mano inside post statistics. How many unassisted attempts at the rim do they get every 100 team possessions? What is their percentage on those attempts? How many rebounds do they get every 100 team possessions? And how well do they limit their opponents from doing these things.
Here is the list of players:
Here are the top five in terms of creating rim attempts for themselves:
Here are the top 15 in keeping their opponents from creating at the rim:
and here are the top 15 in terms of offensive rebounding differential:
Allow me to summarize:
Pek destroys opposing centers on the boards, creates and finishes rim opportunities better than anyone not named Dwight Howard, and holds his own on defense. Don't talk about trading Pek.