MIAMI GARDENS, Fla. -- The San Francisco 49ers’ quarter-century climb back to the top of the NFL mountain will have to continue for at least another year.

In a season defined by their resilience and ability to win in wild and outrageous ways, the Niners couldn’t find the final inches to reclaim their place atop the league’s hierarchy.

San Francisco coughed up a 10-point fourth-quarter lead with fewer than eight minutes to go as the offense couldn’t prolong drives and the defense couldn’t come up with timely stops as the Kansas City Chiefs emerged with a 31-20 victory at Hard Rock Stadium.

In some ways, the game was fitting for a Niners team that played five consecutive December games that came down to the final moments. But it wasn’t the outcome the Niners hoped for after climbing from 4-12 a season ago to the brink of their sixth NFL championship.

“Disbelief,” tight end George Kittle said. “I thought we answered the call almost every single time this season… Just our mentality was we are going to finish this one out. Then when you don’t do it, you want to look in the mirror and ask why.”

The why was a combination of an offense that repeatedly had delivered in clutch moments throughout the season and a defense that consistently provided stops in the waning seconds failing to come through in the final eight minutes.

Instead of becoming the second team to go from four wins to Super Bowl champions in the span of two seasons, the 49ers must spend the rest of the offseason figuring out how to get over the hump.

Although they face the possibility of a Super Bowl hangover, the groundwork has been laid for the Niners to be back in this spot next year.

With coach Kyle Shanahan and general manager John Lynch working in lockstep and empowered by owner Jed York with matching six-year contracts, this turnaround was three years in the making. Following an 0-9 start in 2017, San Francisco traded a second-round pick to the New England Patriots for quarterback Jimmy Garoppolo. He led the Niners to five straight wins to close that season and set off a series of events that changed the franchise's fortunes.

The trade for Garoppolo came in conjunction with other shrewd moves, such as finding gems beyond the first round in tight end George Kittle (2017 fifth round), receiver Deebo Samuel (2019 second) and linebacker Fred Warner (2018 third), big-ticket free-agent signings in cornerback Richard Sherman, fullback Kyle Juszczyk and linebacker Kwon Alexander and under-the-radar additions in guard Laken Tomlinson and cornerbacks Emmanuel Moseley and K’Waun Williams. The Niners also surrendered middle-round picks for receiver Emmanuel Sanders just before the trade deadline this season.

After they spent the past two years climbing from the bottom, the thought of a major leap forward crept into the Niners' collective consciousness April 25, when Arizona used the No. 1 overall pick on quarterback Kyler Murray, leaving defensive end Nick Bosa for San Francisco at No. 2.

"When we were able to draft Nick, I thought this was possible," 49ers CEO Jed York said. "That was something that was really, really important for Kyle was to have a Super Bowl-caliber defensive line."

After trading a second-round pick to the Kansas City Chiefs for edge rusher Dee Ford and drafting Bosa, the Niners had five former first-round picks along the line (Bosa and Ford complemented interior pass-rushers Arik Armstead and DeForest Buckner, with Solomon Thomas as depth). The Niners opened organized team activities in late May and got their first look at their supercharged defensive line.

"When we first put the pads on and we were going against our defensive line, it just absolutely shocked us on offense," Juszczyk said. "They kicked our butts for a good two weeks before we were able to adjust to their speed and physicality. And I think that made us such a better team on offense and defense."

When word spread of an August practice in which Garoppolo threw five consecutive interceptions, the Niners quietly looked at it the other way: This wasn't about Garoppolo struggling nearly as much as it was about the defense having the potential to dominate.

That belief turned to certainty in a convincing Week 6 win against the Los Angeles Rams. As defending NFC West and NFC champions, the Rams were the final measuring stick for the Niners, who opened the season 8-0 and became the second team in the Super Bowl era to win that many consecutive games to start a season the year after winning five or fewer.

In late November, the Niners became the first team in league history to play three straight games against teams with .800 or better winning percentages that late in the season. By the time they sandwiched a blowout win against Green Bay and a comeback victory in a shootout at New Orleans around a narrow loss at Baltimore, the rest of the football world had caught on.

There were big moments, such as Kittle's catch-and-run to beat the Saints, rookie linebacker Dre Greenlaw's game-saving tackle in Seattle and journeyman running back Raheem Mostert's 220-yard outburst as Garoppolo attempted just eight passes in another demolition of the Packers in the NFC Championship game.

The smaller moments behind the scenes were every bit as meaningful. When Hall of Fame quarterback Steve Young addressed the team the night before a Dec. 21 rematch with the Rams, he emphasized the importance of locking in for the stretch run.

A leader affectionately known by teammates as "Uncle Sherm," Sherman reiterated that to his young teammates.

"Sometimes you'd see guys coming to me, like, 'Man, I was gonna go out, but I was thinking about you, man,' and it's almost like they're proud of themselves for doing it," Sherman said. "It's really cool because they're starting to understand the moments."

Heading into the offseason, the Niners will have some difficult decisions and salary-cap maneuvering to do. They project to have only about $16 million in space, with Armstead, Sanders and free safety Jimmie Ward set to be unrestricted free agents and Buckner, Kittle and Sherman in line for lucrative extensions.

If they can solve those riddles, the 49ers will again have a roster loaded with young talent, with most of the coaching staff likely to remain in place. And now, they have Super Bowl experience – albeit of the gut-wrenching variety -- to go with a coach and general manager who have authored one of the most impressive rebuilds in recent memory. All of this gives the 49ers the distinct look of a team that should be able to overcome this defeat and be back in the mix next season.

“We worked so hard and we did all the right things; we just didn’t finish,” Mostert said. “Truthfully, I feel like this just made us stronger. We’re built for this, so it’s not about how hard you get knocked down. It’s all about how you get back up. I feel like this team is going to be back up and running in no time.”