I've been saying the same thing for over a year now. McLaren have lost their will to win.
If they win - great.
If they don't win - no big deal.
Top teams work in a way, where if they lose their No.1 driver, they fight tooth and nail to bring in a suitable replacement. McLaren lost Hamilton and brought in Perez! Yes, you read that right.
...and to compound their poor decision in 2012, they have replaced Perez (who was always going to be a failure), with a complete rookie! Yes, you read this right.
At least Perez had experience, was bringing in big money (to be spent on improving the car) and was a good wet-weather driver, who could look after his tyres better than most drivers.
Until McLaren bring in a top line driver (or create a car which is 0.5s/lap faster than everybody else - unlikely), they will continue to struggle to win races. In 2012, they had (arguably) the fastest car on the grid and none of their drivers were able to beat Vettel, Alonso or Kimi. This was the point that McLaren should've made key changes.
I will say that McLaren have every chance of producing a good car. Their resources. Their staff. Their back-ground. Their experience. BUT without a driver on par with Alonso or Vettel, they have a small probability of winning a title or even a race. Alonso and Vettel are mind-blowingly good. Amongst the greatest ever drivers.
And as for R.Denis. This was the guy who "shopped" his own team in 2007. Made a complete hash of managing 2 great (young) drivers, which resulted in McLaren losing the WDC by 1 point. C.Horner who I rate as the best team principal I have ever seen in F1, would've managed Alonso and Hamilton and seen McLaren win the title in 2007.
McLaren need to try and beat Vettel/RBR. With Button as their lead driver, they have virtually no chance. This is a reality that they must face and attempt to sort out.
Once McLaren hire Alonso, Vettel (or even Hamilton), as their lead, No.1 driver, I predict within 2 years, they will compete for titles and race wins. But until then, they will continue to coast.
Personally, I think they should make a HUGE/ASTRONOMICAL bid for Vettel's services in 2015. After Vettel wins his 5th title this year, they should bring him to McLaren and ask him to do for them what MSc did for Ferrari. They'll have to really work hard for Vettel though, as he won't tolerate their attitude of "coasting" and hoping for the best.