As soon as we get bombarded with high balls to tall players that's when his major weakness stands out. It is then that we wish we have a big physical defender in his place.
The elite teams tend to expose this glaring weakness.
He won loads of headers against bigger players tonight and in first leg against Bayern.
You could go and find a physically more commanding CB but they wouldnt give you the reading of game, leadership organisation that Masch does.
I genuinely wouldnt swap him for anyone in the world.
Edit: Ateltico are about the most physical team going and Masch has been phenomenal against them the past few years about Barcs most consistent player against them. He was about only CB I seen that handeled and bullied back Diego Costa last season.