At the time of Garoppolo's Bay Area arrival, though, coach Kyle Shanahan was hardly set to proclaim his new quarterback a godsend.
In a Wednesday interview with ESPN's Golic and Wingo, general manager John Lynch revealed just how wide the Cousins-Garoppolo gap was in Shanahan's eyes before the 49ers took the league by storm in December.
"I was proud of Kyle. Because I think he knew that this was the right thing for our franchise, and he didn't hesitate. But even then Jimmy had to really prove himself. I think it was really smart. [Kyle] didn't play him right away. He waited until he had some semblance of an understanding of our scheme when he did put him in. And he put him in in a position to succeed. And then I would tell you that Jimmy really impressed Kyle, to the point that he said, This is our guy."
It's not that Shanahan was a Garoppolo skeptic. In fact, the former Eastern Illinois star had a prominent role in the quarterback films Shanahan showed to 49ers scouts last offseason, prescribing the traits required to play in the new scheme.
Still, Shanahan couldn't shake his visions of Cousins under center in San Francisco.
After rewarding his hotshot quarterback with a record-breaking contract last month, Shanahan acknowledged to The MMQB's Albert Breer that the specter of Cousins hung over Garoppolo's early days in San Francisco.
"Yeah, of course, it was there," Shanahan said. "Everyone knows how I feel about Kirk. And for anybody who knows how I feel about Kirk, I think this shows how I feel about Jimmy, the fact that we ended up doing this. I'm not a guy who's going to get excited and just go with the momentum, at all. I usually do the opposite, question it to make sure I'm absolutely confident, and not go with the momentum or the excitement.
"Talking about Kirk, understanding where he could be in the next year, for me to feel this way about Jimmy? It says a lot about Jimmy."
Even before Cousins emerged from Robert Griffith III's overbearing shadow late in the summer of 2015, Shanahan was predicting greatnessfor the Redskins' forgotten backup. When Shanahan was given control of his own team two years later, he immediately set his sights on the prospect of landing Cousins to run his rollout offense.
If Cousins was the apple of his eye, though, Shanahan was already settling on Garoppolo as the class of the fallback options.
"At that time, the only guys we thought were franchise quarterbacks that were being mentioned were Kirk and Jimmy," Shanahan told Breer. "And I knew Kirk wasn't going to be a possibility. And I remember asking Bill [Belichick] personally down at the combine about Jimmy, and very quickly he told me that wasn't a possibility. So we moved on from that. He told me he wasn't going to trade him."
Unanswered prayers, sliding doors, the butterfly effect, blind luck? As far as Shanahan is concerned, all's well that ends well.