I must preface this with the fact that I have not played this, but the descriptions seem to suggest the following with some of the expansion teams...
Suppose that you have a balanced team playing a team that is very pass heavy. "Good football" would have you run a balanced attack. However, here is a strategy for this game...always play the pass burning extra passing cards. If you must run, make the second card you burn a passing card. That way, the other player has less passing cards to play, neutering their offence.
What am I missing?
Note that I am really excited about this game and have ordered a copy...I am just wondering if I should invest in the epansion teams....
You have no control over what card is burned while there is an Offense deck. You must always burn the top card of that deck, with no control of which play you may be giving up.
That said, certainly, you can attempt to pass as much as possible to limit your opponents access to those plays. But of course if he realizes you are trying to that he can counter with pass defenses and you will go nowhere fast.
Hope that helps!