Achieve360points.com usually posts these as soon as they are discovered. Occasionally, these secret achievements are for epic failures, especially if they aren't worth a lot of gamerpoints. It wouldn't suprise me to have 'get fired' as an achievement worth 10 points.
It also wouldn't suprise me to see an achievement called 'diamond in the rough' which deals with finding a player above 85 potential after the 4th round, or something like that.
Either way, can't wait to get this game.