That's not completely true, you can't just learn how to be a Maldini or Baresi in the back.. it's a gift, just like dribbling is a gift. The thing is Pep is always taking over big clubs where he can spend massively so he is always in the possibility to create a team (especially in midfield and attack) that has a lot of quality (and that can play his typical game of high pressing and choking the opponent that's on the ball). He has always been in the possibility to play this way, because he only coaches the best of the best to start with. Therefore he doesn't need 4 Maldini's in the back to get results, and he is just fine with a guy with the qualities of an Alexander-Arnold who -defensively- has no clue what he's doing, but who is great going forward. That was the case at Barcelona, at Bayern and at City, but in all of them, there was never a backline that took the attention in a positive way. Better: a defensive line that occasionally showed very questionable defending. Or Pep who showed very poor decisions, like at Bayern in 2015 where he played a 3-man defense, consisting of fucking Boateng, Rafinha and Benatia against Neymar, Messi and Suarez
. He's an amazing coach and he knows what to do or how to show dominance and play peak modern football, but I'd like to see how his philosophy would work out at a normal club like Fiorentina where he doesn't have the financial strength and where he needs to balance a lot more over the whole squad.