SANTA CLARA, Calif. -- Throughout the four-plus years coach Kyle Shanahan and general manager John Lynch have been in charge of the San Francisco 49ers, their quarterback plan has constantly evolved.

In 2017, they didn't use the No. 2 overall pick to take one of that draft's top quarterbacks because they had their eye on Kirk Cousins in free agency the following spring. By Halloween of that year the New England Patriots offered Jimmy Garoppolo for a second-round pick. Garoppolo did enough to change their minds and landed a massive contract before Cousins hit the market.

It was a bold move but not nearly as bold as what they did Friday, agreeing to send the No. 12 overall pick this year, 2022 first and third-round choices and a 2023 first-round selection to the Miami Dolphins for the No. 3 overall pick. It's just the fourth time in the past 30 drafts that a team has traded from 12th overall or later into the top three. It's the highest pick the Niners have acquired in a trade during the common draft era, according to ESPN Stats & Information.

A source told ESPN's Adam Schefter, it was the culmination of a weeks-long pursuit for a pick in the top five that would put them in striking distance of one of this year's top quarterback prospects.

It's a move that would make character Mike Ehrmantraut of Breaking Bad and Better Call Saul fame proud: no more half measures. The Niners are all-in on acquiring a franchise quarterback for the future

"You talk about blockbuster, this is a decade-defining trade for the 49ers," Steve Young, ESPN NFL analyst and 49ers Hall of Fame quarterback, told SportsCenter on Friday morning. "And it's clear that Kyle Shanahan has not been satisfied with the quarterback position. It has been eating at him for some time and we've talked about it, around it, tried to be more aggressive about it but the truth is this is now the proof in the pudding that they are now going to get their quarterback."

Indeed, the 49ers are going to get their quarterback, which begs two follow-up questions: Who will that quarterback be and what will become of Garoppolo? The answers are intertwined.

Teams don't give up as much as the Niners did for the third pick if they don't have their eye on a quarterback. Garoppolo's injury history -- he's missed 23 of his past 48 regular-season starts because of knee and ankle issues -- has put the 49ers in a spot where they must look to the future if they want to contend long-term.

Assuming the Jacksonville Jaguars select Clemson's Trevor Lawrence first, the 49ers would then have the chance to take BYU's Zach Wilson, Ohio State's Justin Fields, Alabama's Mac Jones or North Dakota State's Trey Lance. Chances are, Wilson will head to the Jets at No. 2, which means the Niners would have their pick of the other three. Or, in a less-likely scenario, the Niners could use the No. 3 pick as part of a package for another blockbuster trade to acquire a quarterback elsewhere.

It's hard to imagine the Niners making such a big move without at least some idea of which quarterbacks they prefer. Fields is a dynamic player with big-play ability the Niners have been missing. He's worked with Shanahan at the QB Collective in the past. Jones is the polished type of pocket passer Shanahan has always liked and would bring down-the-field accuracy San Francisco's offense has lacked. Lance is probably the most unknown because of his small-school pedigree but his physical tools and leadership skills are hard to ignore.

One thing they all might have in common? For all their talents, they might not be ready to start in 2021. Which is where Garoppolo comes in. Schefter reported the Niners have no interest in trading Garoppolo this season. While that could change if the 49ers get an offer that's enticing, it's also possible the Niners will indeed hang on to Garoppolo even with a highly-drafted rookie waiting in the wings, similar to what Kansas City did in 2017 with Alex Smith and Patrick Mahomes.

It's a comparison Shanahan alluded to in December when asked about his offseason plans at quarterback.

"Do you want to go get a starter as a backup quarterback? Then you've just got to decide if you want to spend the majority of your salary cap on your first- and your second-string quarterbacks," Shanahan said. "That's something that most teams do have an issue with, that second-team quarterback, unless they've drafted a guy and then had their starter from the year before. Someone like Alex and what they had with Patrick. So, it's a very common thing. You just hope you don't lose your guy for a whole year."

Moving on from Garoppolo would save the 49ers $24.1 million against the cap but that kind of cap space doesn't do them much good now that free agency's big-money days have passed.

The Niners believe injuries did them in last season and with better health, this is a roster that's ready to surge back into contention. Would that still be the case with a rookie starting at quarterback? History would say no, as no rookie quarterback has started a Super Bowl, let alone won it, in the common era.

Best case scenario outside of a too-tempting trade offer for Garoppolo: he starts, stays healthy and takes the Niners the distance. That would open plenty of trade opportunities next offseason and the Niners could recoup some of their lost draft capital.

It's long been said fortune favors the bold. The 49ers have their chance to prove it. If it works, they'll be able to create the type of sustained success Shanahan and Lynch have searched for since they arrived. If not, it could ultimately be their undoing.

"Kyle Shanahan is going to pick his guy," Young said. "That is going to define his coaching career. ... This is an amazing, life-changing event for a lot of people in the 49ers organization."