I have only one secret : Defense!
All my players are defenses, they have outside and inside defense.
A player's salary increase if one of the key skills for his position is very high (19 or plus).
,but if you build 5/6 defensive players, you have a great advantage.
This is only possible if you buy back players from the others team who have trained them in skills you can't currently train.
As Wagner says, next season the 32 defense will lose his effort.
I've been using the 131-man defense for 2-3 seasons now and hope it holds up.
Finally, I think it's best if I don't keep my roster, because it's not as strong as you'd expect.