They don't defend as a team, unlike Chelsea. Their squad is better or at worst on par with Chelsea, so they have no excuses. The only difference between the two teams is their manager; as much as it pains me to say that, because Pellegrini is one of the managers that I like, and I absolutely detest Mourinho. But credit where its due Mourinho's not only done amazing business in the transfer market with Chelsea, he's also set them up very well.