There are lot of axioms about presidential races that are true until they aren't. That's probably because they're often more about correlation than causation, or even simple mythology (for instance, you've probably heard that the taller candidate always wins, but taller candidates actually have a mere 27-22 winning record). But one axiom that seems well-supported is that governors have an inherent advantage in presidential races. Four of the last six presidents were governors, and Barack Obama was the first sitting senator to win the White House since John F. Kennedy.

There are some good reasons why this is true. Governors can argue that they have directly applicable experience to the presidency, having led a state government that resembles a federal government in miniature, with various agencies to oversee, a legislature to contend with, judges to appoint, and so on. They sign bills, give state-of-the-state addresses, have security details, and generally go around doing things that look almost presidential. Senators (or heaven forbid, House members) talk about "leading" when they mean giving a bunch of floor speeches, which isn't exactly the kind of thing that makes people build statues of you.

So why is it that governors have fared so poorly in this year's presidential election?

There were two former governors on the Democratic side, one of whom (Lincoln Chafee) is already gone, while the other (Martin O'Malley) is struggling. But the really striking situation is among the Republicans, where no fewer than nine current or former governors decided to run for president. Initially, this looked like an embarrassment of riches for Republicans. But it hasn't worked out for them, and it doesn't look like it's going to.

Louisiana Gov. Bobby Jindal's withdrawal from the race on Tuesday makes three governors who have dropped out, months before any votes are cast (the others were former Texas Gov. Rick Perry and Wisconsin Gov. Scott Walker). The six that are left — Jeb Bush, Mike Huckabee, Chris Christie, John Kasich, George Pataki, and Jim Gilmore — are all doing abysmally. The last two are asterisks at best, and the first four stand in fifth, sixth, ninth, and 10th places respectively.

The easy explanation for the governors' poor performance is that this is the year of the outsider on the GOP side, but that tells only part of the story. Governors can certainly claim to be outsiders, since they don't do their work in the moral sewer of Washington, DC. Aren't they out amongst the noble and wise American people, close enough to the populace to absorb its virtues and far from the corrupting influence of the capital?

Perhaps, but it turned out that Republican voters' understanding of what makes an outsider and an insider isn't really about Washington per se. Over the past few years, the party's grass roots have been gripped by an anti-politics fervor that values quixotic crusades over substantive victories, and equates actually accomplishing anything through ordinary political processes with betrayal. Most of all, it defines the party "establishment" — essentially any Republican who got elected before 2010 — as its enemy.

That's why someone like Ted Cruz, a senator who has never written a law and who, if you ask him what he has accomplished, will tell you about the times he "stood up" and failed to stop Barack Obama and his own party's leaders from keeping the government open or not defaulting on America's debts, can still be considered unsullied and thus potentially worthy of the nomination. And those like Donald Trump and Ben Carson, their minds uncluttered by even the remotest understanding of how government works, are the most popular of all.

When Jeb Bush said a year ago that he'd have to be willing to "lose the primary to win the general without violating your principles," he put his finger on the problem the governors would have. Bush, Kasich, Christie — all are extremely conservative, yet have in their histories and inclinations at least a hint of the pragmatism that governing requires. But if you showed it even for a moment, you started this race with two strikes against you.

The reasons governors usually make good presidential candidates — translatable executive experience, concrete accomplishments, an ability to work across the aisle — are disadvantages in the Republican nominating race for 2016. Some of the GOP governors just turned out to be bad at running for president, no matter the success they had in their home states. But if any one of them actually turns out to be competitive — much less win — it would be a shock.