I would respectively disagree. Bush was The GOP choice going back to early 1999. McCain was an upstart. McCain's win in in NH was an orgasm for the MSM. Bush won a tough battle in SC, and then lost in MI. Frankly, Bush had a network set up over the US as a whole which made his candidacy a foregone conclusion, but the MSM was giddy over McCain's early success. After MI, Bush pretty much took over.
George Shultz was the architect of Bush’s groundwork. The organization of people on the ground for Bush was truly amazing, but if you listened to the pundits, Bush was destined to fall to Forbes or McCain because he didn’t speak well and was “unelectable” in the general election because he was so conservative.
The problem is using the term “establishment”. What do you mean by that? I don’t think you will find almost any candidate getting double digit votes that isn’t supported by someone in the “establishment”.