Here are his career stats.
Here's an in-depth analysis of his draft potential when he was coming out of college.
He has had some injuries the last couple years, and I read that he wasn't practicing because of knee soreness. If that is something that will continue, huge red flags go up. I'm sure that is part of the discussion with the Steelers. If he is healthy, and shows his knees will allow him to participate in practice and will recover completely, he is a pretty talented guy.
It all depends on his health, and how much money he's looking for.