Moss is going to be a boom and bust player with Cassel at the helm. IIRC, there were two distinct occasions where Moss had his coverage beat - by a decent/good amount - only for Cassel to not get the ball out there. Moss still has the wheels (something I had been concerned about a couple weeks ago), but the whol reason they give him some slants is to set up the bomb...
with Brady, you were almost guaranteed one of those bombs would hit, with a decent chance to get two - and you never know, maybe even three. With Cassel, you are about 50/50 he will get one, maybe even slightly less, with a shot at a huge 2 bomb TD day, but dont hold your breath. And of course games where they miss on all the big plays and you get 3 or 5 catches for 38 or 52 yards and nothing.
Unless Cassel can become a better QB than he seems to be, its going to be this and while that's a bad situation for a #1 WR, if you have some depth Moss still should help win some games over the year when Cassel does deliver the ball.