Mclaren are going to struggle hard next year. Above people were saying Vettel above Hamilton because when given a fast car Vettel won a title and Hamilton didn't always.
Realistically, Mclaren hasn't actually had the fastest car this year, at times it has, at others it hasn't. When Red Bull have been in the lead.... they can go 15 seconds out, cruise, absorb safety cars, pull out a 15 second gap again, rinse repeat. when Mclaren had the best car, they are struggling to keep a few second lead and the bad pitstops Hamilton had, frankly if those happened to Red Bull in their strongest races, Vettel would have still come out leading... that has been the biggest difference. Red Bull are stronger when they are strong, and less weak when they are weak.
The only time Hamilton probably had the best car and didn't win was as said, with a actually world class team mate, and he missed the title, by one point, in his rookie season, hardly a poor performance and had the team favoured Hamilton as Vettel has had he'd have won that title(and vice versa if they'd backed Alonso completely).
Without reliability issues, the Mclaren could be the best car of the season, with its reliability problems it isn't close, it isn't even really top 3, had it been, Hamilton would likely be leading the title(not only because he'd have I would think 3 more wins and plenty of other points, but most of them would mean less points for Alonso/Vettel).
Over all, even this year the first decent year from Mclaren in the past 5, it wasn't good enough, and it took incredible drives from Hamilton to get any points in the past several races, and fantastic drives earlier in the season, brilliant qualifying and good overtaking to get other points. We know Button won't compete and it will take a small miracle for Perez to do well next season.
That is based off the general idea that I simply can't see Mclaren having the consistently best car, its been years and the mistakes, and all but this season the just no where near good enough car, I can't see it happening.
You can win a title with a average driver and easily the best car, you can be somewhat competitive with a great driver and a meh car, with a average driver and a meh car.... you're screwed.