As 18th-century poet Robert Burns once wrote: "The best-laid plans of mice and men oft go astray."
Kyle Shanahan and the 49ers thought they had it all mapped out. They made a massive swing to move up in the 2021 NFL Draft to select Trey Lance, a talented but raw quarterback who would eventually lead them, along with Shanahan, to multiple Super Bowls. Until he was ready, the 49ers would put their faith in Jimmy Garoppolo, an average, injury-prone signal-caller who they liked enough to invest $26 million in cap space this season to lead the 49ers, but not enough to entrust him with their future.
The belief was that with a healthy Garoppolo and a veteran team, the 49ers could contend for the Super Bowl while Lance dipped his toes in the NFL waters and was brought along at the proper speed.
Stay in the game with the latest updates on your beloved Bay Area and California sports teams! Sign up here for our All Access Daily newsletter.
Six games in, and the 49ers' Mona Lisa is in tatters. The 49ers are 2-4 and are cruising toward rock bottom after a sloppy 30-18 loss to the Indianapolis Colts played during a monsoon at Levi's Stadium.
Garoppolo has played poorly, the offense has been stagnant, and the calls for Lance to start once the rookie has fully recovered from his left knee sprain have been cranked up to 11.
If Shanahan does pick up the scraps of his master plan and put them in the garbage, Lance will be taking up the starter's mantle with much more than the 49ers' season on the line.
The entire operation is teetering on the razor's edge.
San Francisco 49ers
Find the latest San Francisco 49ers news, highlights, analysis and more with NBC Sports Bay Area and California.
The 49ers team that went 13-3 in 2019 and was 10 minutes away from a Super Bowl title is gone. Sure, a few of the key contributors remain. But that 49ers team built on physicality and toughness, the one that took pride in running the ball down the Minnesota Vikings and Green Bay Packers' throat during back-to-back playoff games, is gone.
That has been laid bare during the first six weeks of the season. The 49ers' vaunted defensive line has been just OK. Without a dominant push up front, the 49ers' secondary has been exposed. The takeaways that came so easily in 2019 no longer appear precisely in their moment of need.
On offense, the 49ers lack an identity. Shanahan admitted after the loss to the Colts that he is having trouble finding a rhythm as a play-caller. Once thought of as one of the top offensive minds in football, Shanahan has started to come under fire amid the four-game losing streak. The 49ers aren't well-coached, aren't prepared, can't generate explosive plays, are undisciplined and lack the killer instinct that was the calling card of the 2019 team.
The shine is starting to fade from Shanahan's star. The losses are piling up. The quest to renew the 2019 run is dead and buried along with the 49ers' fool-proof plan to contend for a Super Bowl title while laying the foundation for the next Lance-led decade.
There have been fair criticisms of the way the 49ers orchestrated their decision to draft Lance. Trading two first-round picks to move up to draft a quarterback who isn't ready to play and might have been there at No. 12, or at the very least, in the eight-to-10 range merits scrutiny. If the 49ers wanted to change at quarterback in 2021, Mac Jones, who has had a good first seven games with a Patriots team that lacks the offensive talent the 49ers have, would have been the better play.
If the plan was to draft Lance and set up an Alex Smith-Patrick Mahomes situation with Garoppolo remaining the starter for one season, perhaps mortgaging the next two years of first-round picks wasn't necessary. It always seemed like the 49ers made a move without knowing exactly where they were going.
RELATED: Maiocco: If 49ers wait for Lance to be ready, it'll be too late
So here they sit, from expected Super Bowl contenders to 2-4 and sinking fast.
Plans gone astray, the 49ers now must alter course. But when Lance's era truly begins, the rookie will be asked not only to save the season as best he can, but justify the moves made to get him there and to steady a foundation that has begun to crack in Santa Clara.
The talent is evident. Raw, but clear. Lance has to show promise. It won't be linear. Rookie quarterbacks are supposed to struggle. There will be tough moments and NFL lessons learned. But Lance has to mesh with Shanahan and reignite the offensive genius who took the NFL by storm.
The win totals should, at this point, be secondary. It's all about Lance. Who he is, what he can become and, what he and Shanahan can be together.
Remember, there is no Door No. 2. The 2022 and 2023 first-round picks reside in South Beach. The 49ers have the players that will make up their core -- George Kittle, Fred Warner, Nick Bosa, Trent Williams, Deebo Samuel -- but the Lance-Shanahan partnership will determine how or if the 49ers will rebound from this fall.
So when Lance truly takes over as the starter -- be it this week or in a month -- he won't be tasked with saving the 2021 49ers. He'll be tasked with being the catalyst for the next era, to give the 49ers a new identity, and to keep the whole thing from tumbling down.