Critics contend that Garoppolo remains unproven, his success merely a small-sample-size phenomenon. Defenses will adjust to his accurate strikes over the middle of the field, the thinking goes, forcing him to live outside his comfort zone with more throws downfield and outside the numbers.
That's a tall order for defensive coordinators, searching for answers to the NFL's most efficient offense over the final five games of last season.
Beyond the impressive tape and gaudy metrics, there is ample anecdotal evidence to suggest Garoppolo is here to stay as the 49ers' savior.
When Cassius Marsh was claimed off waivers from New England last November, the veteran defensive end recently told the San Francisco Chronicle, he "called" Garoppolo's late-season emergence before it happened.
"I knew because I was with the Patriots and he would shred our defense every day," Marsh explained. "He'd shred the first team every day, and it looked no different than when Tom (Brady) was on the field. He's a much better athlete than Tom; he's super disciplined and works hard. I'm very happy to have him as my quarterback.
Where have we heard that scouting report before?
If Marsh's testimony was the lone example of hyperbolic praise, it would be easy to dismiss as premature hype. Over the past two years, however, Garoppolo has inspired an endless stream of plaudits from awe-struck, closed-practice witnesses.
Let's examine the most vivid accounts:
"Certainly we have a good quarterback in Jimmy," Belichick added, "and Jimmy could go out there and run everything that Tom can run. We've seen that."
Forced to trade the former Eastern Illinois star a year later, Belichick lamented that he was breaking up "the best quarterback situation in the league."
» The Ringer's Michael Lombardi, formerly Belichick's right-hand personnel man, once insisted Patriots players would line up to testify on behalf of Garoppolo's estimable potential.
"I've watched this guy practice and play for too many practices. This guy is a good player," Lombardi raved last March. "And I'm not shilling for Belichick. ... I'm telling you, he's worth the Patriots to hold onto him. If I was in New England, I'd be telling Belichick every day, 'There's no way we can trade him.'"
Lombardi went on to relay stories of players and coaches walking off the practice field and shaking their heads in disbelief at Garoppolo's ability.
"Ask any player who leaves New England," Lombardi continued. "You can just randomly call a guy. ... They'll all tell you he's great."
» One ex-teammate predicted last offseason that the Browns would immediately graduate to postseason contention if they managed to pull off a trade for Garoppolo.
"I played against him every day in practice. He's all that," the undisclosed player told CSN New England. "He can make all the throws. He can process all the information. He is a gamer. He can slow it down. He can spin it.
"I'm going tell you this, if he had gotten traded to Cleveland, they're a borderline playoff team. I really believe that."
"I've seen him on tape because we had a common opponent in Miami," McCown stated last offseason. "He made some high-level throws and did some things that would get you excited about his ability to maybe carry a franchise. That's definitely on the tape. ... I certainly see why people would give him an opportunity to come in and be a franchise guy."
"Jimmy's got a great arm," Hogan offered. "He's an athletic kid, and he plays really well. So when he gets his chance in the NFL, I think he'll be real successful."
"He was confident. He made good decisions. He made some awesome throws in that football game," Joseph said last February. "I was really shocked how good he was against us."
"He's a stud, man," McVay marveled to San Franciso general manager John Lynch. "He sure is wired the right way, isn't he?"
Garoppolo is sure to endure stumbles and slumps along the path to stardom. Is it fair that he's already one of the sport's highest-paid players after just seven starts? Perhaps not. But the preponderance of data at our disposal suggests the 49ers had no realistic alternative to breaking the bank for the key to their era of new hope, a golden boy deemed untouchable in Patriots trade talks just a year ago.