After looking at the injury report I noticed from 03 right up to 07 most of his injuries were soft tissue.
From 07 on he has began breaking down with more serious tendon and joint injuries including his back both times around Nov/Dec. The one that concerns me most is his recent knee injury involving the MCL.
I guess it reminds me of Stephen Davis. Maybe I'm just over thinking this. It just looks to me like he's starting to break down.
2 back system a must.
SI.com - NFL - Clinton*Portis Injuries