I'll test other positionning rules this week.
For now, I like this one because it forces the defense to anticipate the play and to make field coverage instead of stacking, and allows the offense to simulate fake play, in a sense. But I 'll test other ways, to see what I prefer and what I think it's the most balanced.
EDIT : one thing I can do perhaps is to allow only the free defense men (not the one aligned with offense men) to pivot...or add a rule to allow O tackle or O guard pivot too (to be able to make center dive plays), and to compensate this advantage, allow the same number of D pivots...
So many possibilities...THis game is great
