First, I disagree. Second, its about numbers. Most NFL defenses are built to counter a traditional offense with a barely mobile QB which allows them to effectively play 11 v 10. When you have to commit a player to defend against the threat of a QB run, then you have one less guy in coverage. If Sammy commands your #1 CB and a safety over the top, and Tyrod gets his own man then either someone is left totally uncovered or you have one less guy near the line to play the run. Pick your poison.
Since Tyrod demonstrated his ability to connect on the home run ball consistently and proved to be very dangerous when he pulls the ball down and runs, Sammy has proven to be almost un-coverable, and Shady is still as dangerous as ever, I think defensive coordinators are afraid of us and our offense's big play potential.