Wine critic Jeb Dunnuck is leaving his job at the Wine Advocate, the publication founded by Robert M. Parker Jr., the world’s most powerful wine critic. On July 1 he will launch his own digital publication, JebDunnuck.com. California wine will be a major focus.

“It hasn’t been an easy decision, but it’s something that’s been on my mind for a few years now,” Dunnuck, who lives in Boulder, Colo., tells The Chronicle. “I’m excited to get on to the next phase.”

The news comes as a surprise to many in the wine industry, since Dunnuck had seemed Parker’s heir apparent. “I knew I’d found a younger version of myself,” Parker wrote of Dunnuck when he hired him in 2013.

For a genre whose imminent death has been proclaimed countless times in the past decade, wine criticism on the 100-point scale looks to be a more popular entrepreneurial endeavor than ever.

Dunnuck is not the first Parker protegee to leave the Advocate to start his own venture.

On the heels of major changes at the Advocate in late 2012 and early 2013 — Parker stepped down as editor in chief and sold a large share of the company to a group of Singapore investors — critic Antonio Galloni, whose rapid ascent seemed to portend a leading role in the publication’s future, left the magazine. He founded his own publication, Vinous. (Vinous would go on to acquire another small, enormously respected wine publication, Stephen Tanzer’s International Wine Cellar, along with its team of critics.)

The Wine Advocate subsequently filed a lawsuit against Galloni, accusing him of withholding Sonoma wine reviews that he had written as their employee. It later dropped the suit.

Soon afterward, the Wine Advocate tapped Dunnuck as the new critic of France’s Rhone Valley.

At the time, Dunnuck was moonlighting as a critic for his small wine newsletter, the Rhone Report, while working full time as a software engineer for NASA contractor Ball Aerospace. He worked on high-profile missions including HiRise, which photographs the surface of Mars, and Kepler, a survey of our galaxy aimed at discovering new planets and stars.

A longtime wine lover, Dunnuck had taken a part-time job in 2006 at a Boulder wine shop. “Around 2008, I had a holiday break,” he says, “and I thought I’d create a website.” That became the Rhone Report. Three years later, he started charging subscription fees to his readers, which at its peak numbered 1,000.

“My wife and I would commute to work early,” he says of his schedule in those days. “I’d work from 7 to 3 every day. Then I’d work on the Rhone Report from 8 to 2 a.m.”

Five years into the Rhone Report, Dunnuck received an email from Robert Parker, whom he had never met. “He said, ‘Hey, would you like to join my team and be a reviewer for the Wine Advocate?’”

It wasn’t quite a no-brainer, Dunnuck says — he was feeling excited about the Rhone Report’s growth — but he joined Parker’s team, remaining in Boulder, and took on reviewing responsibilities for Washington state, central and Southern California and, naturally, southern France, including the Rhone Valley.

When Parker stopped reviewing the wines of Sonoma for the Advocate late last year, many assumed that Dunnuck would step into that role. Instead, Lisa Perotti-Brown, the Advocate’s editor-in-chief and longtime reviewer of New Zealand wines, took over the Sonoma beat. Dunnuck says that had nothing to do with his decision to leave.

So why leave, then? “The single-voice model that was so dominant in the past in wine criticism has faded,” Dunnuck says. “Everything has moved toward a brand-driven, team-based approach. There aren’t many people out there with a single voice covering multiple regions. I think that’s a shame.”

He’s right that the leading U.S. publications that score wines on the 100-point scale have virtually all become team-based. Wine Spectator (where I used to work) has long relied on a team of critics, never on a single voice. (One of its longtime critics, James Suckling, founded his own publication, JamesSuckling.com, which remains based on his sole voice but has never gained much critical influence.) Both Vinous and the International Wine Cellar, founded on the individual voices of Galloni and Stephen Tanzer, now rely on the power of their team’s combined expertise.

Covering the entire world of wine seems like a big job for one guy, even a guy who worked on the Kepler mission. Which is why Dunnuck says he’ll only be focusing on regions he loves: Washington, Bordeaux, the Rhone and southern France — and all of California. As with Wine Advocate and Vinous, tastings are mostly conducted with regional organizations and through individual producer visits. (Wine Spectator, by contrast, tastes wines blind in its offices.)

Like the Rhone Report, JebDunnuck.com will not accept advertising. Annual subscriptions will likely be $100 for consumers, and $150 for the trade. Not all content will be behind the paywall.

Although no other critics will score wine on JebDunnuck.com, Dunnuck says he’ll “be thrilled to have other articles written by other writers,” mentioning Wine Advocate contributor R.H. Drexel as an example of someone whose voice he’d welcome.

Dunnuck’s contract with the Wine Advocate runs out on June 15. After that, “it’s gonna be a mad dash to create content” in time for the launch, he says. He plans to “gut (his) own cellar” to write some retrospective reports. On June 18, he begins a trip to Santa Barbara, Paso Robles (San Luis Obispo County), Santa Lucia Highlands in Monterey County and the Santa Cruz Mountains. Those tasting reports will be online by the end of July.

Calling for a return to the single-voice model of wine criticism sounds a lot like a return to the earliest days of the Wine Advocate, which Parker began in 1978 from his basement in Monkton, Md. Parker, then a lawyer, was long its sole voice. And was it ever a voice: Parker gained his incredible influence not by keeping his head down, but thanks to his strongly expressed, initially controversial views and tastes. His most famous proclamation — that Bordeaux’s 1982 vintage was its greatest in decades — flew in the face of most critics at the time, and then came to define a generation of wine style. And a generation of wine critics.

Maybe Parker wasn’t so wrong, after all, when he called Dunnuck a younger version of himself.

Esther Mobley is The San Francisco Chronicle’s wine, beer and spirits writer. Email: emobley@sfchronicle.com Twitter: @Esther_mobley Instagram: @esthermob