Roger Theder, who helped engineer one of the most memorable upsets in Big Game history as Cal’s head coach and who later became a mentor to several prominent high school quarterbacks in Northern California, has died from complications from Parkinson’s disease. He was 77.

Mr. Theder led the Bears from 1978 through ’81. In his tenure, Cal went 17-28, beating Stanford twice, in 1979 and ’80.

The 1980 victory probably ranks as the most significant for Mr. Theder. A 2-8 Cal team was using backup quarterback J Torchio in place of injured Rich Campbell, who would be a first-round pick of the Green Bay Packers in 1981. Stanford was 6-4 with a quarterback named John Elway and would have gone to the Peach Bowl if it had beaten the Bears.

The final: Cal 28, Stanford 23.

Carolina Panthers head coach Ron Rivera, who was an All-America linebacker at Cal, played two seasons under Mr. Theder.

On Monday, Rivera tweeted, “#RIP to my 1st @CalFootball HC Roger Theder. You believed in me & offered a scholarship 2 @CAL which I will 4ever be grateful. #GoBears.”

Mr. Theder made his reputation as an offensive coach. He began his career as an assistant to John Ralston at Stanford in 1968.

After four years, Mr. Theder moved across the bay with Mike White, joining White’s staff at Cal. The two helped put together one of the West Coast’s best and most sophisticated offenses in the mid- to late-1970s.

In a phone interview Monday night, White said that Mr. Theder “had a unique skill in offensive football and he’d done his homework and research. The way you win over players is to be an expert in a particular area. He was an expert in offensive football.”

Among the quarterbacks Mr. Theder coached at Cal were Vince Ferragamo, Steve Bartkowski (the NFL’s No. 1 pick in 1975), Joe Roth and Campbell.

Mr. Theder replaced White as Cal’s head coach after the 1977 season. After Mr. Theder was let go by Cal in ’81, he took jobs as an assistant coach in the NFL with the Colts and Chargers. Mr. Theder was the offensive coordinator at San Jose State under Ralston in 1993-96.

Over the past two decades, Mr. Theder, who lived in Orinda, worked as a tutor to high school quarterbacks. He trained several who made it to the NFL, including Ken Dorsey, Trent Edwards, Dennis Dixon, Josh Johnson and the 49ers’ Colin Kaepernick.

In a 2011 Chronicle story, Mr. Theder said, “I don’t make any promises to any kid. I’m not saying, ‘If you come with me, I’ll get you a college scholarship.’ That’s why a lot of parents send their kids to me. But it’s up to the kid to get the scholarship, not me.”

Not only was Mr. Theder a quarterback at Western Michigan in the early 1960s, but he also was a catcher on the baseball team. He played in the College World Series.

Still, football was his passion.

“He was a football junkie,” White said. “He was football through and through.”

Funeral services are pending.

Steve Kroner is a San Francisco Chronicle staff writer. Email: skroner@sfchronicle.com Twitter: @SteveKronerSF

Theder at Cal