I sense making up something because it utimately didn't happen.
Falcao, Soldado, Di Maria's inability to settle at United, Robinho, Cavani, Morata, Forlan, Morientes, Deco, Suker etc.
Plenty players failed from La Liga to PL.
Plenty great players failed when moving leagues - Cannavaro, shevchenko, kaka, hazard, zlatan Ibrahimovic, schweinsteiger, robben, sneidjer, jerome boateng at city vs Bayern, Gnabrybat Arsenak vs Bayern etc.
The fact he didn't move is a solid reason - especial since he played for one of the most technical teams that were built towards his style in his league almost from his debut days that had Eto"o Ronaldinho, xavi and iniesta - the success has been dribbling down bit by bit as the quality of player has not been so legendary.
It was a perfect time to move these days but I was not surprised that he didn't do it and signed a nice contract instead.
And again - don't think that i am saying Messi will be a complete flop in a different league playing for a different club - I just don't believe he will be able to play the same standards we have got to see from the Messi that has played for Barcelona all his life, La Liga all his life, amazing goals vs getafe or getting to react off the abilities of iniesta, xavi and ronaldinho etc all his life.