This is a cautionary tale for Kyle Shanahan, John Lynch and the San Francisco 49ers. In between endlessly perusing the warts they seem to find on Jimmy Garopollo, they might want to share a moment or two reading the French philosopher Voltaire, who once wrote “perfect is the enemy of good,’’ before they do something they may live to regret.

If Voltaire’s words don’t make them pause for a moment, then they should remember the name Drew Brees and how he got to New Orleans.

Brees got there in 2006 because the San Diego Chargers convinced themselves they’d win more games with Philip Rivers than a damaged Brees, who was coming off a severe shoulder injury and had had his ups and downs since the then-San Diego Chargers drafted him at the top of the second round in 2001.

Brees had far fewer ups and many more downs in those first few years as an NFL starter than Garoppolo on his way to posting a 24-9 record with the 49ers that included a 2-1 playoff record and a fourth-quarter lead in the Super Bowl. Brees was 10-17 between 2001 and 2003, had thrown more interceptions than touchdowns and then was alerted by Chargers’ assistant Brian Schottenheimer that the team might draft a quarterback high in 2004.

Schottenheimer once related that Brees responded by saying, “That would be the worst mistake ever.” Turns out the Chargers took Rivers but he didn’t win the job, and Brees went to the Pro Bowl and led San Diego to an 11-5 record and its first playoff appearance in nine years.

Despite that San Diego still only saw the warts on their pint-sized quarterback. They tagged Brees to keep him around for one more season but never fully believed in him, as evidenced by a “long-term” contract worth $50 million but that only paid him $2 million in its first year and was heavily incentive laden. Brees played under the franchise tag instead and went 9-7 while completing 64.6 percent of his passes in 2005 with a then-career high 3,576 passing yards before tearing his labrum in the season finale.

Soon after the Chargers moved on to Rivers and Brees left so sign with the Saints.

That next season Brees led the league in passing yards and four years later was the Super Bowl MVP. The Chargers are still waiting to win a Super Bowl, and they won’t do it with Rivers, who retired this year.

The similarities are eerie between the pre-Saints’ Brees and Garoppolo. Both were on teams that seemed anxious to replace them despite obvious flashes of potential and winning seasons. Brees had injury issues and had shown some inconsistency. Same is true of Garoppolo, who has struggled particularly with injuries, starting only 25 of his last 48 games.

Yet Brees’ unheeded warning to the Chargers could just as easily come from Garoppolo because, when healthy, he wins. And when he’s not healthy the 49ers lose. As we said, San Francisco is 24-9 with him under center since his arrival in the middle of the 2017 season. But perhaps more significantly they are 7-27 without him over that time period.

This is not to say he will be Brees, who became one of the most prolific passers in NFL history. What it says, though, is that the 49ers win a hell of a lot of games when Garoppolo is at quarterback and not very often when he isn’t. Isn’t that the quarterback’s chief responsibility? Finding a way to win games.

Still, Shanahan and Lynch keep “evaluating” the quarterback position, and many speculate they have their eyes on someone like young Sam Darnold, the Jets' quarterback who is 13-25 in three years as a starter. One can argue the strong-armed Darnold has suffered with extenuating circumstances, the largest being the Jets’ organization’s utter ineptness at building a football team. Nevertheless, he’s 13-25 while Garoppolo is 19-9 and one shaky fourth quarter away from being a Super Bowl champion in the same time period.

Others believe Shanahan is pining for Deshaun Watson, the Texans unhappy young quarterback who is not likely to be traded no matter how much he complains, or even Kirk Cousins, with whom he has previous experience. Kirk Cousins? Talk about warts. He’s got warts for two.

While Cousins does answer the bell every Sunday, he’s 52-53-1 in his nine-year career when he does, the last six as a starter. He has only managed to get two teams into the post-season and, unlike Garoppolo, the only way Cousins has gotten into the Super Bowl is by buying a ticket.

Might the 49ers be legitimately concerned about Garoppolo’s injury history? Yes., except his arm is fine, and he has that knack for winning. Might they believe they can upgrade themselves? Yes, but they control a guy for two more years who has led them to victory 72 percent of the time he’s been under center at a cost of about $25 million a season which, these days, is about what you’d expect to pay.

Who is coming in and winning 80 percent of the time? Probably nobody.

So what should Shanahan and Lynch do as the quarterback carousel turns and turns this offseason with three starters already having been traded and rumors exploding that there will be more to come? What they should do is be careful whom they jilt.

Perhaps Shanahan has convinced himself there is a better looking option out there for his team than Jimmy Garoppolo and maybe he’s right, but not so many years ago the San Diego Chargers felt the same way about a damaged young guy named Drew Brees.

How’d that work out for them?