That's only really because of the hugely unpopular engine development rules I reckon. From a standing start after years out they got pretty close (in relative terms) with a bit of a punt. If they were allowed to go shit out with tokens they'd have made a lot more inroads. I don't think McLaren were the right test bed team for Honda but I can see that reaping rewards without too much time passing. It's not like Renault have done anything special at all and are still supplying a top team.