As has been rumored for several weeks, Ezra Klein is leaving The Washington Post and the Wonkblog he started for greener pastures — in this case, greener because of all the dollars:

But when Klein proposed the creation of an independent, explanatory journalism website — with more than three dozen staffers and a multiyear budget north of $10 million — the Post said enough is enough. Indeed, Jeff Bezos, the Post’s new owner, and Katharine Weymouth, its publisher, never even offered an alternative figure, sources familiar with the negotiations said.

Now, Klein is set to take his talents elsewhere. The Washington Post’s Wonkblog account tweeted the announcement Tuesday that he is leaving: “It’s official: Ezra is leaving the Post. Hoping for the best for him.”

As early as this week, Klein is expected to announce a new venture — described in a memo to Post staffers as a new “news organization” — that will look to staff more than 30 people on the editorial side alone. Meanwhile, the Post, which for four years has benefited immensely from housing the Ezra Klein brand — Wonkblog averages more than four million page-views a month — will lose its star columnist and its claim to some of the most widely read policy analysis on the Internet.

There are a number of easy #HotSportsTakes on this. The Washington Post is stupidly letting a star leave again. This is just like when the Politico guys tried to start it within the Post then had to go elsewhere. This is just like Nate Silver, Kara Swisher/Walt Mossberg, Bill Simmons, etc. But I keep coming back to a few facts:

— More than $10 million is not a small amount of money for a newspaper whose revenues have done nothing but decline over the past half-decade-plus. It is a small amount of money for Jeff Bezos — which would seem to indicate that, as Bill Grueskin smartly notes, he sees the Post as a business, not a civic-minded charitable organ of his empire. (The man built his empire on efficiency, lean supply chains, and thin margins — this isn’t a shock.) Back in 2006, the Politico guys were looking for $2 million, and the Post was in a healthier state financially, gliding on Kaplan money.

— Wonkblog is very good, and I have no doubt that whatever Klein creates will also be editorially strong. Along with his analytical talents, he also brings an appreciation for what online audiences value. We don’t know much about what NuevoWonkblog will look like, beyond that it’ll focus on explanatory journalism. But it’s hard to imagine a news site about policy issues, no matter how social ready, that would generate enough advertising to pay for an expense outlay that large. The Politico story said Wonkblog currently gets 4 million pageviews a month, which The Atlantic’s Alexis Madrigal notes is

The strangest thing here is that 4 million pageviews a month is … downright modest. http://t.co/BOc69eEY3V

— Alexis C. Madrigal (@alexismadrigal) January 21, 2014

Even if that number is wrong, as Brad Plumer says, it’d take an audience much larger to generate enough online advertising revenue to pay for that kind of overhead — which will also have to include more tech/business-side headcount as an independent entity than as part of the Post. How much can explanatory journalism scale? If there are nine questions about Syria that you’re too embarrassed to ask, are there also…nine questions about Namibia? Nine questions about Medicare policy in Missouri? A much larger staff can produce a lot more content, but I’d wonder if there’s a ceiling for that kind of content, and whether or not it’s high enough to pay for an operation this big.

— That said, and this can’t be emphasized enough, we know nothing about how NuevoWonkblog plans to make money. If it’s just advertising, I think there are some real, legitimate questions. But one could easily imagine other ways to generate revenue. Sponsored events. A high-end database strategy, gathering public data and making it easily searchable for a price. A premium, industry-based vertical product like Politico Pro. Syndication. Custom research. A TV tie-in at MSNBC. Some of these make more sense with a Wonkblog ethos than others, but given that its subject matter is the most powerful institution in the world, there’s plenty of money floating around to be snared. Until we get a handle on how this new entity plans to make money, it’s really impossible to know whether letting Klein go was a smart move or not for the Post.