Genereal Man Of The Match Tips:
Just put 10 players of that position on and obviously your goalkeeper. It doesnt matter if you have a defender up front, it will count has a defender MOTM and so on. (Vincent Kompany is a very good Defender to put up front, trust me he has good accuracy)
For a defender to be Man of the Match, you need to put in some good tackles and maybe get a goal with a defender. The achievement will unlock after defenders have been Man of the Match 50 times.
Note: This does not need to be the same defender 50 times and does not include your opposition getting man of the match with a defender.