I don't think the offense caused the defense to get tired, at least not in the 1st half. TB had 3 drives to start the game which comprised of 7 plays for 64 yards and 2:45, 9 plays for 41 yards and 5:10, and 14 plays for 71 yards and 7:22. The offense only had 1 drive opportunity in all that time which they drove for a TD. And like I said, the defense gave up the TDs before the half and end of game too easily.
I know the broadcast team commented on that with Gregory, but if you look at the hand-off, it was high and not in the center of the RB's body; it was almost in his armpit.