Click his name, look on reports, and it should say were he plays best and what role/s suit him.
Obviously but that alone what do it, a lot goes into how well your players responds to your tactics. Some tactics will fit others as may be the point for Belhanda and Utaka but may not suit Giroud. Also could be the players your surround him with, just because IRL Montpellier won the Ligue 1 does not me the FM12 team will. You may have to bring in new players or move around your tactics so he molds easier.
Yeah thats true but just checking his reports alone is sometimes enough. It normally is for me, thats why I suggested that alone.