This may sound mental, but ill give it a shot
When creating a player, what may add an extra play element to the game is an experience system
Like, say every skill has a max of 100
And there are (guessing) 10 skills that each player can have,
This would mean that you would need 1000 points to max a player
What if you were only given like 300 or so points to play with
and then by playing games (perhaps in its own game mode) you could either add earned points to stats, or like pro evo, the stats would increase on their own in relation to how much experience was gained.
Whether this game mode should just be the normal world league, or a new game mode where you only control the single player and not the rest of the team is a totally different discussion.