Bills Interested in Marcus Stroud

I must say I was surprised about the news that the Bills had Jaguars DT Marcus Stroud in for a visit, as a preliminary move to a possible trade. I was not aware of his availibility, and I'm still surprised why. Stroud is a beast, 6-6 and 310 pounds. I've seen him and fellow Jags tackle John Henderson basically shut down teams running games. I remember Greg Wiliams once admitting to me that the Bills didn't even try to run against them.
But here's why Stroud may be available. He's missed 12 games the last two years. He had ankle surgery in 2006. He was suspended 4 games for steroids in 2007, and missed more time after re-injuring the ankle. He'll also be 30 years old by training camp.
But its all about what you have, and what he'll bring. Stroud would be a major upgrade on the Bills defense at tackle, and a nice combination with up-and-comer John McCargo.
The question is, what would the Bills have to give up? The trades for Kris Jenkins (Jets) and Shaun Rogers (Bengals) sent 3rd and 5th round picks to the trading teams. The Bills have extra picks in those rounds, and that's how this deal may get done.