I don't think it was that much about the injury (although he did avoid contact at times). The main problem was that at first he was playing too deep and too alone quality-wise. The optimal situation is Xavi getting the ball on the attacking side of the field and having Messi, Iniesta and Dani to rotate the ball with, thus making it hard to mark all the options out. Stuttgart was pressuring high and Xavi was dropping way too deep to get something done. Once he got there, the two options he usually had to build the play with were Yaya & Busi and the duo didn't really know how to make space for themselves with the pressure. Once Messi started to drop deep too and Iniesta move around the midfield, the game started to open. Once Yaya was out and Henry in (+Andres truly back to midfield), the second half was much better. Though it was always to be, since it was clear that Stuttgart wouldn't be able to apply that kind of pressure for the whole game.