Benitez is a defensive specialist through system, not necessarily through improving players. Compare that to Jose, who not only drills his players into fantastic systems, he also improves them markedly in terms of quality; see Nuno Valente, Paulo Ferreira, Ricardo Carvalho, John Terry, and took the likes of Walter Samuel and Lucio to new heights near the end of their careers.
They're both excellent...as well as borderline insane when it comes picking apart tiniest details about the player to improve his game or exploit weaknessess, its just that Jose can drive his players better...for a while anyway.
In fact, I'm pretty sure Luiz himself credited Benitez for his vast improvement this season. Mourinho's edge over Benitez in terms of player development comes from his ability to improve their commitment and dedication. Was it Ibra who said he would kill for Jose? But special quality sauce at mostly vanished the moment Mourinho left. Within couple of years Snejider went from Madrid reject to best player in the world only to end up in Galata.
Either way I gotta say no world class manager really had a knack at Luiz yet, since Carlo and Interim One didn't really have enough time, so it might be a good idea to keep him around, if only to see what Jose can do with him.
Anyway the whole transfer saga was bollocks (big surprise

. Milan's solid defence probably had more to do with the fact that the likes of Maldini, Nesta, Stam and Costacurta all played in that defence at different periods.
I don't know about that, Lazio-era Nesta and Milan-era Nesta wasn't even the same guy.