The “investigative series” that the conservative Daily Caller commenced this week about the liberal media watchdog outfit Media Matters for America and its founder David Brock accomplishes the impossible: It makes me sympathize with Media Matters and Brock.

This is no small accomplishment, as I’ve never thought much of Media Matters’ style of watchdogging or Brock’s journalism. I don’t mind Media Matters’ partisanship. Partisans often serve journalism by spotting unseen truths. I don’t dislike anybody over there; a couple of veteran journalists of my acquaintance produce copy for it. And I’ll be the first to admit that Media Matters’ giant media trawler captures much embarrassing — and occasionally useful — information about conservatives and conservative media.

That said, I always approach the group’s findings with the same reservations I do prosecutorial briefs or opposition research. What are the authors leaving out? Media Matters, like so many think tanks and watchdogs, is in the propaganda business. Yet even a propagandist deserves a fair hearing in the press. But the Daily Caller fails to clear even that low hurdle. As someone who routinely finds valuable nuggets in partisan media squabbles, I kept waiting to be shown something that wasn’t predictable political point-scoring. But it has yet to emerge.

The first installment in the series, which appeared on Sunday, relies on conjecture and anonymous sources to portray founder David Brock as a paranoid loon who hired bodyguards to protect him from death threats. Brock may indeed be bonkers, but you’ll find no proof of it here, only whispers. The piece claims Brock “struggles with mental illness,” but presents no evidence outside of anonymous sources referring to his alleged “bouts of what appeared to be mania” and a 2002 Drudge Report item that maintains he had a breakdown in 2001 and was treated in a psychiatric ward.

Another anonymous source tells the Daily Caller that Brock “completely lost his shit” in a 2008 meeting outside of San Diego, causing “a lot of conversations about David’s mental health.” Another anonymous source — a “prominent liberal,” no less — tells the Daily Caller that Brock was “erratic, unstable and disturbing” at a 2010 meeting. The piece, written by Daily Caller Editor-in-Chief Tucker Carlson and staffer Vince Coglianese, also claims that: “At some point, Brock received a prescription for his condition” and cites an anonymous friend who says Brock wasn’t “trying to keep” his illegal drug use (including cocaine) “a secret.”