Of course some are not 100% his fault (although Canada is IMO) but he has to take a portion of the blame for them.
Jenson is more than able, Lewis clearly can't, he's jumping ship. It interesting that Mclaren have got better season by season since JB joined, they're were regressing between 2007 - 2009 when Lewis was leading the team but have moved closer to the front since 2010 when Jenson joined. Those are the cold hard facts.
That might actually be a fair point, if were not for the fact Hamilton has performed better in 2 of the 3 seasons. If what you are saying is true, and Button has somehow made the McLaren team more intelligent and creative, then what good is it if you can't drive well enough on track?