1) almost unique amongst modern bigs in that is a GOOD thing half the time -- he simply cannot risk fouls and take himself out of the offense. Roy Hibbert or Joakim Noah backs off guys driving and you are wondering WTF, that's what we pay you for. Cuz backs off and half the time its praiseworthy -- don't get the cheap foul.
2) he's not a shotblocker but is being used as such. I am confident almost any non-shotblocker being put in that defensive anchor position would have at rim results in the same range as bad. The difference is that Blake Griffin is never asked to stand back there and somehow redirect a wave of drivers coming his way.
3) and there is a WAVE of drivers coming this way as our backcourt defense is simply the worst in the NBA
4) and despite all that its hard to find the team defensive stat this year where we aren't better with him on the floor. DRTG, Defense per 100, Opp PER whatever. He leads us in basically every individual defensive stat both raw and advanced. best shotblocker, best stealer, best defensive rebounder, whatever.
The main problem is that he's being asked to be a shotblocker, and he just isn't. But who is that on exactly? If they decide Blake Griffin is the guy to go to at PG with CP3 out and he fails, that's hardly Blake's fault. And for All Star purposes the key thing is that only 1 of his main competitors excels in that shotblcoking role himself. And none of the other guys is even asked to do it. You can't say "oh that Boogie, he sure doesn't defend the rim" without acknowledging that Love, Aldridge, Dirk, Blake, Lee, Randolph etc. don't defend the rim either. The difference is that their organizations don't ask them to and they are rarely thrown out in that situation. They have to defend heir own men only, and come over on help sometimes against guys likely already with 1 defender still on them. Of course their percentages are going to be higher. Stick Dirk or Blake back in the paint alone and tell them to try to block or alter IT and Ben's men coming screaming around the corner all night and their at rim defensive percentages would plummet too.