Whatever happens with development its going to be hard for Hamilton to forget, and he shouldn't that in the first 9 races, Hamilton has lost a hell of a lot of points down to ridiculous Mclaren mistakes, pits and strategy.
You can win titles not being the best car on the grid but you HAVE to take the points when you can get them, Hamilton is being prevented from doing so by the team more than the car. He really should be 1st right now which would help and have helped maybe cover for a poor Silverstone and poor next couple races if they don't jump back up time wise.
Vettel was just miles ahead of Hamilton's times, but had there not been a terrible pit stop and really a little more strategy, he'd have really had a very good chance of doing great in that race. He was passed at a pit stop, other cars dropped out, he could and should have picked up so many damn points in that race. In the last two races they've twice sacrificed being 0.5 or 1 seconds slower earlier in the race, to leave him being even slower than that at the end of a race.
but add up all the places lost, the Maldonado incident, where he could have finished at Valencia despite being just no where near Vettel's pace(he could seriously have won the freaking race if he had 2 laps extra on each earlier stintand managed to keep Alonso behind him on track). Mclaren could and maybe should lose Hamilton because, fast or slow car, Hamilton should currently have for me, 30-40 more points than he does now out of the team screwing Hamilton over.
This weekend even Hamilton saw that pitting early to cover for Grosjean was ridiculous, it cost him that stint, it ruined their strategy and ruined the final stint costing him further places.
If the car isn't the best but the driver manages to be competitive, then the team absolutely destroys any chance you really had, you need a new team.