Sadly, he has a better recent history than McFadden. Tate had an awful year last year, but the previous year averaged 4.3 YPC on 181 carries for Houston. He also averaged 5.4 and 4.3 his first two years with the Texans (albeit in a backup role).
I don't dismiss him for that reason. If we can bring in McFadden, who averaged less than 3.5 YPC each of his past three years, I don't know if we can say Tate wouldn't end up being the better player.
Now, I think there are better players out there for us to consider, but I'd be OK with Dallas bringing in Tate for look-see rather than doing nothing at all. He's still young and like with McFadden (with everyone blaming Oakland's line for his three years of failure) there may be circumstances that led to him suddenly falling off last year after three good years. He's more proven than any of the backs we are currently carrying.