...I do think that with advanced stats, people seems to confuse "tough minutes" with "riskier minutes".
At that level of play, everything is tough. Scoring is tough. Entering the zone is tough. Going into the corner against Chara is tough (wich is something you have to do with a faceoff in the O-zone).
So to me, Plekanec isn't playing the "toughest minutes". Only the "riskier" ones. And in that regard, I think he is perfectly rated: better than average.
Reading some posters, you'd think he's the perennial Selke winner. C'mon, guys. He isn't that good, at least not anymore. Yet he's good and valuable.
I'll add something about him: He may be playing the "riskier" minutes (or tougher minutes, if you like). But the fact is: it is not tough to play against him. You'll never pay the price, he won't win more than 50% of the faceoffs, and more often than not, his line won't score. The only area where he's really THAT good, is on the PK.
Now. It looks like I'm downplaying him, but not at all. One of the top PKer in the league who's better than average at playing the "riskier minutes", it is a good thing to have. But certainly not untradable.