The Republican nominee began his path to the White House by getting his plane shot down and then surrendering to the enemy. Okay, JFK got his start when, as he modestly told a reporter, “They sank my boat.” But at least he didn’t surrender afterwards. And, yes, McCain spent 6 years as a POW, enduring confinement and torture while leading his fellow prisoners in resisting the conditions imposed on them by the enemy. But this tells us nothing about his executive ability, which in fact has never been tested.
What has been tested is his “maverick” status in the Republican party, and his integrity. He was on the edge of the saving and loan scandal as a member of the “Keating Five.” He more or less rehabilitated his reputation after that by co-sponsoring a campaign finance reform bill. But he has taken opposite sides on several major issues since then, most notably offshore oil drilling, torture, and immigration reform. That doesn’t exactly make him a maverick. It makes him a pseudo-maverick, until the bills come due, at which point he buckles under to GOP orthodoxy. One can reasonably expect him to do the same on pork barrel spending and the culture war issues, like the sanctity of marriage as a bond between a man and one woman at a time. His position on taxes and health care is already well to the right of many other Republicans.
The most significant variable in his campaign is whether the GOP leadership likes him enough to bother stealing another election for him. While I might enjoy having lunch with him, that does not make him qualified to be the Leader of the Free World.