I think this is happening for a lot of teams in all the major european leagues. I don't think it's a coincidence that Neymar is going to miss the next four weeks with an injury starting the day after their loss in the Copa del Rey. Same sort of situation for Ronaldo right now. I don't think he wanted to miss the Spanish cup final, but I certainly believe the upcoming WC has something to do with his current availability. Sergio Aguero is another guy that comes to mind. He was on fire early in the season, but has barely played lately because I think he's resting for the WC.
I don't think that's the case, at least with Barcelona and Real Madrid, which are the close ones to me. Ronaldo is a psycho, Jordan, Kobe like, and there is no way he misses a final, against Barcelona no less, if he can avoid it. His injury is real, I saw the game when it happened, and the same goes for Neymar.
Messi is the puzzle. He has no known injury, yet he just doesn't run. All he does is walking around. The spanish media and fans were cracking jokes about how he barely covered more distance than Pinto the keeper, against Atletico Madrid in the ECL.
And trust me, it's perfectly possible that Messi moves. Of course, only whenever and wherever he wants to and at an obscene price, but Barcelona right now is a hell for the players. Messi was so booed by some fans yesterday that he told one of them 'go back to work, boludo'.
And it goes beyond the pitch (If you already know all this stuff, skip the rest hehe).
FIFA has suspended Barcelona's trading rights for one year because they broke rules regarding underage players.
The persident Sandro Rosell resigned because the Neymar transfer was declared at €57M (which nobody believed) and turns out the tribunals are finding out that it's at least double that amount, with at least 40M going straight to Neymar's father. There is speculation that this could explain in part Messi's current state.
Of course the coach is done, so that adds to the turmoil, along with many cornerstone players failing to deliver be it due to age or other reasons. That inclues impending departures from leaders Pujol and Valdes.
Their current FO is also quite poor, 'building' a roster with redundant moves while not addressing glaring holes that they won't be able to patch next year unless the FIFA bails them out.
Really, Barca is currently the New York Knicks of the soccer world, a place usually held by Real Madrid, and in that environment, I wouldn't be surprised the least if Messi took one crazy offer from one of the Arabs, for instance.