I think when training a player's special ability between 1-50 or 1-40 then you get an offer for a player and you decide to sell that player the progress should be kept at whatever number you trained the player up to. For example if it acquired 20 of the 50 points needed to learn a special ability, I can then sell that player while keeping the progress of the special ability. It actually respects the true value of the player and purpose of training special abilities. Also it would make the transfer system a bit more entertaining than it is now, while getting true value for players with potential to impact teams that can be invested in.