Last week, the Democratic presidential primary field shrunk considerably. Two declared candidates, Lincoln Chafee and Jim Webb, dropped out, sending their several dozen supporters into a panic about which remaining candidate to back.

Current Vice President Joe Biden also announced that he would not be entering the race, disappointing journalists all across the spectrum, from DC types hoping for a "Democrats in Disarray" narrative to the editors of The Onion.

That leaves Hillary Clinton, Bernie Sanders and that other guy who has a "The Wire" character based on him. Oh, and Lawrence Lessig, which is a name that I did not make up.

Why is the field clearing now, so early in the race? It sure isn't because mounting a presidential campaign is gruesome, tedious work that only a handful of viable candidates could ever possibly attempt. The current Republican primary has taught us, if anything, that it might be too easy to run for president these days.

It isn't because Democrats don't have a reasonable bench of executives and electeds around the country who could keep America on the kind of path that Barack Obama has set for us. My conservative readers will disagree, probably, but by pretty much any objective measure, we're all better off than we were in 2008.

And it isn't because Democratic primary voters are united behind a single candidate. Though Clinton has led consistently in the national polls and in most state polls, she is facing a serious and robust challenge from Sanders. Her support is far from 100 percent.

The reason is because Clinton has shown, repeatedly throughout this campaign, that she is simply the best.

I'm using "best" here as a noun. I mean, sure, we can use "best" as an adjective to describe a lot of what she has: organization, fundraising, husband, message discipline and so on. Certainly, her 2008 campaign, in which she finished a strong second, gave her a massive edge in connections, personnel and experience coming into this cycle.

But after this last week, it's hard not to simply say she is the best. And yes, I am talking about the Benghazi hearings on Thursday.

It's true that both Biden and Webb bowed out before Thursday, and Chafee really should have, so I don't think you can say that the hearing was why the field thinned considerably last week. But you can say that Clinton's performance during the hearing was unquestionably emblematic of the kind of campaign she has run and of the kind of president she would be.

Let's imagine, for a second, a counterfactual, that Republican front-runner Donald Trump had to sit through eleven hours of a committee hearing going over the minutiae of one of his many abject failures – one of his four bankruptcies, say, or season 10 of "The Apprentice" – and how he would react to the interminable questions, interruptions and ramblings of the self-important.

Trump wouldn't have made it ten minutes. He would have stood up, flipped the table, screamed something about how "yuuuuge" he is and stormed out of the hearing.

This is not simply because Trump is a lumbering sack of indignation and ego – though, of course, he is. It's because, while he may be the best at self-promotion, he doesn't get what makes a good, let alone the best, president.

Clinton, on the other hand, has things figured out. You can compare her testimony this past week to her January 2013 testimony, when she famously erupted at Wisconsin Senator Ron Johnson, yelling, "What difference does it make?"

Last week, she was calm and poised throughout the much longer hearing. Reports are that she meditated during breaks, and I think that's great. I would much rather have a president who knows when to pause and re-center before making a decision than someone like Trump – or, say, George W. Bush – whose whole schtick is based on impulsive outbursts and quick decisions.

Clinton had joked recently that Republicans were her enemy, something Biden disagreed with and even reiterated in his speech declining to run. But I don't think you can look at what happened in the hearing on Thursday and not conclude that she was, in fact, being beaten up simply because she was Hillary – and some Republicans are not above coming right out and saying that their repeated hearings are designed to drag Clinton down.

In this way, the questions Clinton last week faced brought out something many people thought Clinton, who has lived in the white-hot national spotlight for more than two decades, had completely lost. As Matt Taibbi put it this week at Rolling Stone, "These morons in Gowdy's committee ... ended up making her look like the one thing she really isn't, at least not very often: a regular person."

This will not be true for everyone. I try not to talk politics with my mother, for example, but she cannot stand Clinton. After 20 years of Rush Limbaugh and Fox News, she is convinced that Clinton is underhanded, responsible for untold atrocities and out to destroy the American way of life. But my mother isn't going to vote for Bernie Sanders or Martin O'Malley either, and Clinton didn't have to convince her.

She has to convince people like Taibbi, whose politics lie closer to those of Sanders, and moderate Republicans who fear President Trump or President Carson. She has to convince the Obama-loving millennials who might not want to vote for someone's grandmother. She has to convince people like me who are on the record from the last time around that, dangit, we don't want to vote for another Bush or Clinton.

Unlike Taibbi, I was always willing to believe Clinton was a regular person. Instead, to me, what this past week's Benghazi mess and what the thinning crop of candidates opposing her really show is that Clinton is ready to be president, and that she would be good at it. It turns out I can see myself voting for another Clinton – because Hillary is the best.