Isn't exactly a "adaptation", this dont exist in TE. As t@tomu mentioned, when u buy a player, or he is good, or he is bad.
And, thats what I was saying, I was talking about "what regulates" the amount of "good-well programmed players" that you can have. And as I was saying, the game, regulates and add limits in all teams. You can not have, "8" excellent key players, the game will assign, more contribution to some players, some will score, few others, assist, maybe another player, will be aggressive etc...
This is the "assignation of contributive roles", that do a limitation inside all teams to keep a sense.