-Did you see the Napoli-Chelsea first leg???? Yes I did, and granted Luiz didn't have a good game, Chelsea's defense in general was an absolute disaster under AVB. If you have watched Chelsea at all under Di Matteo, David Luiz has improved drastically due to the defensive stability around him now. He can easily be coached on positioning by Pep, he has all the raw skill and ability, he just needs the right coach. Again, which is why he shouldn't be an out and out starter if we got him this summer. He would learn boatloads under the guidance of Pep and Puyol.
-there is a reason why Guardiola has benched him for the important games and why Sir Alex let him go The reason why Guardiola benched him was because he hasn't been as concentrated and focused as he has been in previous seasons. Idk where your coming up with back-up at best, Pique is world class and he was playing really well until Valdes had to go and run into him against Chelsea. There is a reason why Pique started every single game in the World Cup, and its no coincidence that they only conceded twice the entire tournament.
-There isn't a position on the pitch where Cesc can do anything close to what Messi does. Did you watch Cesc at all when he was at Arsenal? He practically played in a very similar role and area that Messi occupies now during his best years at Arsenal. Granted, he doesn't do things in the same manner that Messi does, but he was fantastic 2009-2010 scoring 23 goals because of the free role he had as the attacking midfielder who plays right behind the strikers, a position Messi coincidentally plays similarly here.