Rondo's play, while improved, doesn't compare to Posey's. Period. It's an illegitimate comparison. Rondo's a ballhandler whose job is to defend the other guy's distributor. Posey, on the other hand, is a reserve whose job is defense, length and spot-up shooting.
They do different things, entirely. One does not offset the other - unless you want to try revising history again.
And Brown was an outstanding clutch rebounder during his minutes, along with shooting, length and defense. As stated above, no Brown, no title last year. He was most assuredly not our "worst rebounding big."
TP to Jon for some informed comments on the subject.