I loved watching Rosicky at Arsenal in the late 2000s so when he came out of my Hero pack I was fairly indifferent. Not a top end player like we all hoped for but at least he looked usable and was a player I personally liked IRL. I used him as a super sub for a few games and he performed very well, so I tried him as a CM in a 442 and he was ok, but after some experimenting with tactics and players I landed on the 4411(2) with him as the CAM. Just put him on free roam and everything else on default and man... what a card. He is a great old school CAM. Get the ball to him, RB/R1 your way through midfielders and drop perfect passes to your other attacking players. Hes not going to blow the doors off defenders (especially top end ones like Militato etc, but hes the player you want on the ball driving at CBs while other players make there runs. Great second runs in the box as well.
Use him like an oldschool CAM (like David Silva, Juan Mata etc) and let him get on the ball and be the focal point of your attack and he works very well.