Can we stop it with this nonsense? Button hasn't had a major setup problem like he had last year (tyre temperature issue) - the car is just very limited due to it's poor ride and low downforce. Lewis would have pulled out his two tenths on Jenson in qualifying but in the race they'd be running together at the same pace. Their three years showed that they have very similar (and excellent) race pace unless one of them had a setup or mechanical problem.
As for the silly season, I'm hoping Perez doesn't continue at McLaren. Nothing against him - he's a solid driver and seems like a nice kid, but he's not going to beat Button. A better car would likely mean he'd be farther behind. Alonso would be very interesting, but I don't see that happening. McLaren doesn't need Massa's money, so Hulkenberg would be the most likely candidate. Or they are really convinced by the raw pace of Magnussen they could give him a learning year on the job. He probably would do as good a job as Perez as far as points scoring (which is to say, not nearly as good as Button) but could show that turn of speed that they're looking for from the other driver.
Edit: added second paragraph
It obviously cames from inside McLaren that they aren't really happy with driver performance