Murray's actually been on the decline since about the AO 2010. That tournament was the best tennis he had ever played, and he has not replicated that feat. Of course, he was slaughtered by three-years-past-his-prime Federer in the final.
From late 2008 to early 2010 Murray could win matches even against the top players with guile, movement and cat and mouse exchanges. Now he can only win when the other guy is having a bad day or is adversely affected by the conditions.
Sure, Murray failed to lose the Olympic Gold against weary five-years-past-his-prime Federer, who, again demolished him three weeks earlier in the biggest tournament of the year. But again, there was no Nadal standing in his way, just like at Wimbledon and again at the USO. Had Nadal been there, Murray would have put up a fight but crumbled as always because Nadal does everything Murray does except better.
Murray did fail to lose the US Open as well, but he didn't even need to play particularly well there. He just needed to let the few guys left (no Fedal) fall around him due to fortuitous weather and favourable scheduling. I mean I give him credit where due, but he is nowhere near the big three and DelPo yet.
Bills looking good, will win Super Bowl.