The NFL has made this position very very different then it once was and very hard to play. The last line of defense was always a spot where you could would and should remove a player from the ball by laying him out. The defenseless receiver rule has almost made this impossible. A safety now has to wait till a guy makes a football move before hitting him, an almost impossible decision to make in the heat of the moment. Therefore the spot is now really not a place for guys who lay the wood anymore. Its better for the ballhawks with great speed who can protect the backend with sideline to sideline speed excellent ball skills, great football awareness, and tackler.
I think KP fits the mold but the degenerative knee is an issue. Hill can lay the wood, be interesting to see how he does in deep coverage which he didnt see much of this year. saw a bit of nickel (mayb15 snaps) and can play around the box, definitely has value. Brown can ball hawk but did give up the back end a few times and Rolle is better around LOS.
It may be time to draft a kid who can be a center fielder while the other guys hunt for the ball and play the LOS and run.