Hmm, but in the 2 seasons Maradona was at Barcelona, he didn't win La Liga once. Serie A is lower standard than La Liga in general.
But yeah, it will be interesting to see how Messi does if he transfers to another team next season.
You seem to not know much about his stay at Barcelona: he was ill with Hepatitis and then came the dreadful incident with the broken ankle (after a tackle from another player. He had to take injections pretty much for the rest of his career as that ankle was chronically inflamed). Then the xenophobic mania against him culminated in the mass melee in the 1984 Copa del Rey final after which he was sold. He still managed to win the Supercup and the Copa del Rey.