The play call rush/pass split and the rushing inside/outside split could be reduced from the current four textbox input model to using only two. i.e. a player could enter either rush % or pass % and the other value would be 100-x.
The advantage is less input effort/error for the user and less validation on (at least) the server side. The display for the other percent value could be calculated and displayed client side, then calculated server side either on an as needed basis (lazy) or at form submit. (aggressive) There would be no loss of ability for the user's game plan.
This concept could also be applied to the formation rushing inside/outside values.