On Tuesday, Kevin Drum, one of the liberal blogosphere’s most popular writers, announced that he was leaving the Washington Monthly. After over four years there, he told readers in a short post that, as of Friday, he’d be working for San Francisco-based Mother Jones.

The Washington Monthly is so well known as an incubator of journalism talent—think Jonathan Alter, James Fallows, Katherine Boo, Jon Meacham, and dozens of others—that departures are a de facto part of the operating plan. The non-profit magazine’s low pay scale (and a recent very serious cash crunch, exacerbated by its chief financial backer’s losses in the housing market) has never screamed sustainability.

“We didn’t know if we could keep the doors open,” says editor-in-chief Paul Glastris.

No matter. Drum says the Monthly’s financial whirligig wasn’t much of a motivating factor in his move. “My paycheck has been pretty steady,” he drolly noted. And, he says, he’ll be making the same amount at Mother Jones. “It’s not pay,” insists Drum. “I’ve always had this thought that columnists shouldn’t be at the same place for more than five years—maybe they shouldn’t be columnists for more than five years.”

During his four years at the Monthly, Drum produced the bulk of the magazine’s online material, contributed print pieces (mostly book reviews), occasionally joined editorial meetings by speakerphone, and commented on early drafts of articles by other authors.

And, of course, he used his widely linked blog to encourage subscriptions and promote the magazine’s long-form work.

That was part of the idea back in March of 2004, when, temporarily flush with a grant from the Schuman Foundation, the magazine asked Drum, then a tech industry marketing consultant writing the Blogspot-hosted Calpundit, to come aboard. He was recommended by Monthly contributor Josh Marshall, who was already writing a one-man version of Talking Points Memo.

“This was very early on in the blog revolution,” says Glastris. “Other magazines were trying to turn their writers into bloggers. We didn’t have the staff to do that. We barely had the staff to put out a magazine.”

As Glastris tells it, they were one of the very first (if not the first) magazines to hire an outside blogger, one who had built his own audience: “He just wrote his way on to the national stage. He just did it on his own.”

Drum thinks he was an excellent fit at the New Frontier-ish Monthly, both politically and stylistically. But how will his moderate, often-academic and data-driven approach fit in with his new home, which, to paint with an overly broad brush, is named for an IWW orator, was born out of Ramparts, and was once (briefly) edited by Michael Moore? “Mother Jones is more interested in the environment, in social justice issues. The Washington Monthly is more into wonky, neoliberal, political stuff than Mother Jones will ever be,” says Drum.

The disconnect prompted some grousing in his farewell post’s comments section, prompting Drum to post a chiding addendum: “I really recommend you take a fresh look at MoJo if you haven’t seen it since the 70s.”

Rightly so. Today’s Mother Jones is its own (glossy, well designed, and National Magazine Award for general excellence-gobbling) creature. (Disclosure: I worked there in 2005.) And they’re thrilled to have him.

“We got him, really, the old fashioned way, with a long and persistent courtship,” says Monika Bauerlein, who along with her Mother Jones co-editor, Clara Jeffery, has published several print pieces by Drum. “We never thought of Kevin’s work being very different from what we do. Quite the reverse.”

“He’s a very research-based blogger, he’s into finding facts and being in a fact-based conversation,” she says, noting that she think that approach fits about as well as a blogger can with the magazine’s investigative ken.

Drum’s hiring comes less than a year after Mother Jones hired David Corn, The Nation’s Washington editor, to run its booming D.C. bureau. (Until this week, that office was shared with, yes, the Washington Monthly.)

“Of course Kevin isn’t in D.C., but the Internet has made it much easier for someone who doesn’t take Metro to be in the D.C. conversation,” says Bauerlein.

Clint Hendler is the managing editor of Mother Jones, and a former deputy editor of CJR.