My friend, I feel for you, I've already addressed this in another post.
Your #2 controller which controls your halfback will not have access to the "Truck Stick" or the "Stop-Step Juke", in cooperative play. I've researched this in every game mode, whether it be franchise or superstar mode, and exhibition play as well. I initially thought it was because SS mode is intended to be a single player game mode.
Then I thought it was maybe a flaw because I use a Logitech wireless controller in slot 1, and he uses the normal PS model.
No dice. We started a franchise after our SS got corrupted after 9 games (GRRRRRRRRRR), no truckie or jukie for him either. No truckie or jukie in exhibitions co-op either.
It's just another one of those things that EA forgot that they'd hoped we wouldn't notice. At least your "Hit-Stick" still works, and I don't even use the truck or stop single player, but it isn't your imagination, it's not going to work.