I've been noticing that a good amount of people, when using players from the Legends promo, aren't powering them up.
This game is run on AP, and the Legends promo players don't get any discounted abilities until you power them up.
Furthermore, once you power up a Legends promo players, you get the discounted AP in an another slot.
For example, 95 Ronnie Lott. 95s get 2 discounted ability slots. 95 Lott gets 3 discounted ability slots.