http://www.azcentral.com/members/Blog/KentSomers/72572

Here is an article stating the McFadden has been burned a lot in Arizona.  I always wondered why the Steelers were not more interested in starting him and keeping him, how Townsend coud keep beating him out.
He seemed pretty steady in 2008, but so did Gay.  My guess was that he was not a good practice player, or kept blowing assignments, but it is hard to know.