Well... We all would love to have an answer to that question, but I think now we'll just have to wait 10 more days until the US Open and keep our fingers crossed
Some people are suggesting Murray didn't want to go far in Cincinnati because he wanted to rest properly for the US Open... I don't know about Murray, but I don't think David would do that on purpose, doesn't look like him and he seemed pretty distraught about his performance.
But in a way, it might be a good thing. If his performance was the result of playing too much lately, that gives him 10 days to rest and practice for the US Open.