I can see what you're getting at but if you consider the rule changes that were happening in the middle of practice this weekend and the fact that the weather prevented much dry running on Friday, I don't think it's as bad a situation as you're making out. Some strategies haven't gone their way but what about China and Canada, were their strategies awful then too? Plus there were good results in Australia and Spain.
Since 2009 when Whitmarsh took over, McLaren have finished an average of 2.3 in the WCC (including current standings). When Ron Dennis was in charge from 1980 -2008 (I know he left as team principal in 2009 but that was at the start of the season so isn't worth including) they finished an average of 2.7 in the WCC so I think Whitmarsh is doing pretty well and far from being hopeless. Let's not forget that the last time they won the WCC was in 1998 so it's not a recent thing that they've played second fiddle to whoever's won.
Ferrari haven't exactly had a stellar past couple of seasons either have they? 2009 was a complete write off and the 1st half of 2011 and this year haven't been great either. If McLaren continue to keep missing the podium then I agree that they need to re-evaluate their game plan but until then, I'm going to give them more time.