Non tradable players

I have always heard that EA does not always listen to their customers, but I have a suggestion that I think would make the game much better. I have been inconvenienced by the fact that players after the promo ends become “locked” or not tradable. I am not sure why that is part of the game. I might have a player on my roster from a certain promo, and after a week or two, I’ll have that player replaced by a higher overall player. The problem is, now that player who was one of my best is absolutely useless to me. I now have decided to trade in all players at the end of promos to get more coins and tp but this only benefits me when trying to get mythical cards through training to level 8 and competing the set. I have found that this is only one of two ways to utilize the old players. I am not a fan of this because now at the end of each promo, my overall dips down significantly. This would be a simple fix and would make the game so much better especially for young players who might not understand that aspect of the game. It can be very frustrating when working hard for a card just for it to become worthless.