I think your right, its only a matter of time before Marvin has a monster game. The Reggie Wayne/Stokley freakshow this week is good for Harrison owner I think.
Opposition teams have clearly seen now that double teaming Marvin is only going to leave Reggie wide open. Sooner or later Reggie Wayne will get some respect from opposition Defenses, and when that occurs, Marvin will benefit greatly.
I think this week could be Marvin's week. The Jags clearly have one of the best run Defenses in the league, the Colts could easily air it out, Jax passing Def is no where near as good as their run Def. If Edge doesnt get the job done, expect Peyton to go to the air lots.
I think the days of Marvin getting 1500 + 15TDs are over. But 1200-1300 yards + 10TD is something he is definately capable of. That's money.