What? It's a big game. Mourinho will always set up to defend, Pep will always have his teams out to dominate. What on earth do you think Mourinho would manage to do with a midfield of fernandinho, B Silva and D Silva? He would have no idea what to do with them and would leave them on the bench like he always leaves Mata. Pep would put Mata in the midfield 3. That's unheard of for Mourinho, though it also wouldnt work for him because he doesnt know how to set them up to play the way Pep does that makes players like Silva in midfield actually work.
The gap between the 2 squads is mainly there because of managerial quality. Mourinho makes our players look worse. Pep makes his look FAR better.