Interesting results then. If they are picking weird defensive calls at random, which aren't beneficial based on the user play call, and not based on the play type tag, then I don't really see how that would be any more beneficial to the game experience than in previous installments.
Logic tells me that the AI should choose plays based on the exact same thing that real Defensive coordinators do; down & distance and the offense's player personnel package (not formation).
EA could even make it more realistic as well by using down & distance and personnel package along with user tendencies; eg the current user profile only runs 11% on 3rd and 5 or longer with their current 11 personnel package (ignoring the formation, which isn't known until the offense breaks the huddle and the D call has already been made; but even if thats not favorable the AI could make adjustments to package or play selection with a simple audible or individual assignment change).
I know that would be slightly more difficult (time consuming) to code, but its not by any means outside the realm of possibility. And how many problems would that solve (players tweaking and fighting about sliders, for instance) while providing a more realistic challenge? AI doesn't have to cheat, it could use your own (past) tendencies in certain situations to decide what to do. That's what coaches and coordinators spend all week doing, studying their opponent's game film and tendencies.
"If its in the game, its in the game." isn't that what we've all wanted all along?