its simple!
i thought this at first... its actually a great little system because it STOPS you from being able to have lazy strikers chase back like Rooney, or be a box to box workaholic like Kuyt etc...
Basically, if Gerrard can shoot from distance, that is an ability card and CANNOT be switched on or off. Its jusy something he can do, when you're controlling him or when he's playing against you. Simple, just like the old star system.
Then there are tactical cards, like a guy who plays a certain way... trys to beat the offside trap, overlaps on the flanks etc... these are tactical options that replace the arrows etc... in the formation setup.
Like I said, its great because you can't ask someone to do something they wouldn't/can't do in real life. These and these tactical options alone are what can be turned on or off, depending on whether you've asked the player to be attacking/defending etc...