As an 'SC fan, I can definitely say he's better than Kalil. He might not have a better body of work due to injuries, but when he's healthy he's one of the best run blockers of the Pete Carroll era.
I've personally watched him on live TV punk Marvin Austin in the High School All American game (when both were HS Seniors) and then a sophomore Ndamokung Suh against Nebraska when he was a freshman in '06.
He's not the most athletic, but he has elite strength and power to drive back DL's. If he can get over the injuries, he'll be a Pro Bowler for sure.