People in the locker room not liking him at all because he pussied out of games with 'injury' while he told teammates he was fit, as the captain. Was there when it happened. Of course during very tough times at Schalke. At the same weekend (day after the game) going out getting drunk, smoking.. (seen that myself)
A mentality problem... can't go more into details on a public forum sorry. But like I said.. this was a few years ago and I can only hope he changed when he actually comes here. Before all that I actually liked and rated him a lot.
