I would make this trade in a heart beat. You're getting the best player in the trade, and that is the bench mark of a good deal. Wilson is in a great position now, and for the first 4-6 weeks he has nobody to challenge him for carries. That's a 4-6 week try out to be the work horse in a high scoring offense. Caughlin already said that WIlson will get the gaol line carries now as well. Big Ben is an unnecessary add on. I actually like Tannehill more this year. I would try to get a WR back or maybe a low level RB for depth. However, I would still do the deal to get Wilson, then maybe trade Big Ben or Tannehill.
Your giving up Tate, who will get carries, but is still a back up. Baring an injury, Foster is still going to get 75% of the snaps, and 90% of the goal line work. Tate is worth more to the guy you're trading him to then he is to you. McFadden is always injured. He was dreadful last year, and his performance was blamed on the blocking scheme. Truth is, he had NO supporting cast. He doesn't this year either. Flynn has a noodle arm and Prior is so raw that neither QB will drop defenders in the secondary. Mc Fadden will still face 8-9 in the box and will still average under 4 yards per carry. Oh and the Raiders defense is not a "shut down" unit so the Raiders will be playing from behind and throwing a lot at the end of games. Loosing Run DMC is nothing to worry about at all.