(Since man coverage is the only scheme worth anything against quick-snapping opponents...)
When the opposing offense runs plays with a wideout that stays behind the line, so that the outside cornerbacks cross the line to defend. Then the quarterback simply runs into the endzone. I'm sure there's a play that can defend that, but that's a pretty dirty tactic I see again and again.
Winning this mode comes down to performance on extra points, and accumulating double-pass TD's. But not getting greedy on the latter.