I posted this in the World Cup thread:
https://www.youtube.com/watch?v=8bX0ii6g6iw&feature=player_detailpage
Look at the 0:54 mark, the 0:57 mark, and the 3:54 mark. It's a mannerism folks, not a sign of his conditioning.
That's all good... with the exception that you are assuming he hasn't done anything physically exhausting prior to those moments shown in the video... and also and more importantly - him holding his jersey and shorts is not the only reason we think he's gassing - his intensity falls dramatically after 2-3 quarters of play. He practically stops driving, he's having trouble keeping up in D. In close ups he clearly seems like he's out of breath and struggling physically, etc.
In a way, his conditioning being a problem would explain a lot of weaknesses in his game, especially in second halves of the games. If he doesn't have conditioning problems, then our problems and worries about him should be much more serious.