Just a small idea for the future.
We have seen that sides have made an impact on how a team plays and how a squad is dealt with nowadays (and ultimately, the value of a player on occasions).
What I propose is in the future, that players who only have one side are permitted to train a second side at an additional cost (could be primary ab's, could be monetary). I wouldn't advocate the ability to train a third side and be proficient in all three but if such a thing were permitted, I'd suggest a very high cost of either ab's or money).
Obviously, this would change things quite a bit and it might be better to keep things as they are now. But its just something I thought of.