Brice McCain was rated 104 out of 113 CBs overall in 2012 (>25% of team snaps.) His coverage rating is what hurt him, putting him at 107th. His rush, run, and penalty ratings were middle of the pack.
Brice's company down that low in the ratings includes Nnamdi Asomugha and Janoris Jenkins.
Brandon Harris did not meet the >25% of team snaps, so we have a smaller sample size and larger population comparison. He rated 167 out of 217 CBs overall ( no minimum playing time.) Harris was middle of the pack in all areas except penalty, where he rated 211 of 217.
Harris equaled K.J.'s penalties, but K.J. did so in 1030 snaps compared to Harris' 177 snaps.
Ratings courtesy of ProFootballFocus