I realize Messi is the 2nd best footballer of all time or whatever but if you're Koeman I mean..
I can see how having an aging squad while the biggest player in your club's history is basically pulling all the strings would undermine your authority a great deal.
I mean you can't really rebuild the squad around a player who is 33 years old, even if he's the 2nd greatest footballer ever, and Barca's squad is a fuckin aged shambles.