it screws up your game if you plan on simulating anything. if you are the bears and make their receiver scheme SPEED, devin hester becomes a 94 overall and i had him lead the league in yards and tds and he's awful in real life.
and you set your depth chart up in the menus and then you go into the game and realize all the players you have suck! it's a lot of fun! for instance, in my 2nd year i drafted a new qb to develop behind cutler, he isn't exactly young anymore. cutler is an 89 in my depth chart in the menus, the rook a 72. i go to play the first game of the year, cutler gets injured on the 2nd series, i figure i'm boned. go check out the depth chart and in the game the rook is an 85 overall (!!!!) and cutler an 83, so in reality the rook is better in game but when i started him the entire year in my SCHEME he sucked ***, completed less than 60% of his passes and threw 25 picks to 18 tds, so yeah, lots of fun those schemes are.