I always try and manipulate MOM for exactly the same reason as pcmacdanial.
I have a 29 yo 7* striker who needs these points to maintain his rating. If another player is outscoring him during the game and it's not tight I sub that other player.
So far he's got 15 MOM from 29 games, far better than the 100 or so Green packs it would have taken to train that increase and in probably 7 or 8 of these games it's my tinkering that's enabled him to get the reward.
I keep him on FK duty for this challenge just for that reason, and as I've defenders weighing in with goals am top at the moment