5.- A central defender.
Maybe not only one, but two central defenders are what Leo Messi needs. Gerard Pique is not the same player he was a decade ago. The other two options have never been above average.
Samuel Umtiti only had a good moment after his arrival at the club. Clement Lenglet also had a small good run last season but this institution needs better players.
The names of Matthijs de Ligt or Virgil van Dijk sound like great options for Barcelona. Messi is aware of the players he needs in order to improve.