Maicon was good, but imo Juan was the best of the back 4 in Brazil. And I mean strictly defense, not his goal or other situations where he was a danger up front.
Usually in WC best starting XI's, rarely a player outside the top 4 makes the final 11. It happens only when someone has a monster tournament and brilliant 5 matches, like Stojkovic in 1990 or Hagi and Preud'homme in 1994. Juan has been really excellent, but not really better than some CBs who made the final 4 and who have the advantage for playing great till the very end, in the toughest matches.