Well yeah I get your point, but I think Murray is very much in his prime right now and still he hasn't won a slam. Hasn't come even close to it.
Yes Murray is capable of beating the best in best of 3 matches, but doesn't have that next level in him to beat them in majors.
Murray's game is based on consistency, while on other hand Delpo when in the zone is very hard to beat even by the best(much alike Safin).
And of course you have to bear in mind that Delpo is younger and injuries were setback for him in the last 1-2 years.
Watching Murray losing finals again and again I can't see him having what it takes to defeat Federer/Nadal or Djokovic at a final of a Major...