Scouts are extremely powerful and game-changing only if you can constantly feed green packs on him.

Powerful free-kick, corner taker, midfielder or even GK are game changers and easily be the key to success.
But this strategy is also a bit risky as if he can't play (especially due to cards or injured during the match) you will find yourself in great trouble...

Instead of scouts a load of good performing roast players is less risky but also less flashy compared to teams with an ace player.