Ballack is the player I chose with FUT swap ICONS, and I have no regrets. First of all, just look at his stats, he's so complete, he's 1m88 and he has double 4*, without playing with it you already know he's a good choice.
The lower stats on his card are pace (72) and dribbling (78) so I decided to play him with Engine chem style as a CM in a 433(2) alongside Jorginho and Kanté (yes I'm a Chelsea fan), but I don't know what EA smoked because he certainly doesn't feel like 72 pace ingame, he's surprisingly quick, and if you add his physical stat let me tell you, when Ballack runs no one take the ball from him. His shooting and passing stats speak for itself, he rarely misses a shot or a pass. I don't dribble so much with him as I pass the ball around a lot which is what you're supposed to do with Ballack and Jorginho as your midfield. Defensively, his physical will help a lot to move a player and take the ball away. So overall, I don't see any weakness on Ballack, if you need a CM and don't know who to choose as FUT swap ICON I'd advise you to go for him, you certainly won't regret it.
Powerful shooting, so powerful goalkeepers would rather concede than lose a hand
Passing of high quality
Physical beast (which helps both in defense and in attack)
You won't dribble the whole opponent's team and chip the goalkeeper like Neymar would do, appart from that... I don't know