Jimmy Garoppolo is well on his way to making his private quarterbacks coach look like a prophet.

And in the process, Garoppolo, himself, is virtually assured of making a healthy profit with his salaries in 2018 and beyond.

Former NFL quarterback Jeff Christensen has been working with Garoppolo on his mechanics from the time he was entering his junior season at Rolling Meadows High School, near Garoppolo's home in Arlington Heights, Illinois.

Christensen explained on The 49ers Insider Podcast why he said what he said to a young Garoppolo.

“When he was a senior in high school, I said, ‘If you keep this up, you’re going to make a lot of money playing football in the NFL, son.’ And Tony (Garoppolo’s dad) would kind of, ‘Oh, don’t say that.’

“Then, in his sophomore year in college (at Eastern Illinois), I said, ‘You’re going to make $100 million.’ “

Christensen said he was driven to make such a bold projection based on a lot more than just Garoppolo’s footwork and quick release.

“I know the mechanics are going to get better as he takes more reps...The other components, the moxy and the drive and the expectation of being great, that’s why I said it,” said Christensen, who runs "Throw It Deep," an academy for quarterbacks and wide receivers.

“The interesting part is when I said it to him, he said, ‘Well, that’s what we’re trying to do here, right?’ And it was serious. It was a serious comment. And I said, ‘Yeah.’ And he said, ‘All right, let’s get to work.’”

Garoppolo will make approximately $3.5 million over his initial four-year contract, which expires at the end of the season. If the 49ers and Garoppolo do not work out a long-term contract extension before the start of free agency in March, the 49ers have no other realistic option but to tag him as their franchise player at a price tag of more than $20 million for one season.

“I’m very content and happy with what we have now, but that’s the thing that’s good for both of us,” 49ers coach Kyle Shanahan said last week. “We’re not trying to figure out some long-term thing right now which I think is fair to him and fair to us. We’ll see how this goes. I think we’re all in a pretty good situation.”