49ers' rebuild effort proving a success

The 49ers became the NFL's only remaining undefeated team when the Baltimore Ravens gave the New England Patriots their first loss of the year Sunday night.

And with San Francisco playing unquestionably its biggest game of the season against the division rival Seattle Seahawks on Monday night, perhaps it's time for an introduction into the NFL's most surprising powerhouse of the 2019 campaign.

New to the bandwagon - or you're simply unfamiliar with how a team that went 10-22 over the past two years suddenly finds itself with the league's best record halfway through the schedule? We're here to help you ahead of the 49ers' biggest game in years.

How did they get here?

This is the culmination of a two-season, organization-wide rebuilding project started by coach Kyle Shanahan and his hand-picked general manager, John Lynch, who were both hired in the winter of 2017 following two one-and-done coaches, Jim Tomsula and Chip Kelly. They tore down nearly the entire roster and entered their first season with a giant question mark at the game's most important position: quarterback.

With journeyman Brian Hoyer under center, the new regime's first season began with an 0-5 record before Hoyer was benched midway through a game in Washington for rookie third-round pick C.J. Beathard. The losses piled up and San Francisco began the year 0-9.

But the team made a franchise-altering trade at the Halloween deadline, landing Patriots backup quarterback Jimmy Garoppolo for a second-round draft pick. He started the final five games, all wins, helping his new team become the first in league history to start 0-9 and finish 6-10.

Garoppolo not only played well during that stretch, he was one of the best quarterbacks in the league. His 8.44 yards per attempt was the most among all signal callers. His 297 yards per game was third and the team's 28.8 points ranked fifth after the team scored just 17 per game during the first 12 weeks.

It led to Garoppolo getting a five-year, $137.5 million contract the following winter - on the strength of just seven NFL starts. Sure, he looked like a franchise quarterback, but there was considerably risk in signing a deal with nearly $50 million in true guarantees for a player that had seen such a limited sample size during his first four NFL seasons.

The hype of the 5-0 finish in 2017 led to high expectations surrounding the 49ers in 2018. They were widely considered a club that would make a jump toward playoff contention with Garoppolo under center. But he tore his left ACL in Week 3, adding more fuel to questions surrounding Garoppolo's viability as a long-term solution, despite the promise he showed in his first season with San Francisco.

The 49ers finished with a 4-12 record, down two games from the previous season, with the No. 2 pick in the draft. That led to taking pass rusher Nick Bosa, who is already a star providing a massive boost to a lackluster pass rush, in addition to Dee Ford, who was also traded for a second-round pick after getting the franchise tag from the Kansas City Chiefs.

The appeal of the 49ers to Bosa and Ford was simple to understand. They joined a team that was far better than 4-12, a record which was mostly a product of losing the franchise quarterback three weeks into the season (on top of a slew of other injuries all throughout the roster, which led to San Francisco also overhauling their player performance staff this offseason).

So here they are, 8-0, thanks largely to a defense that's been the best in the conference led by the defensive line, where Bosa and Ford are complementing interior rushers DeForest Buckner and Arik Armstead. Offensively, Garoppolo has been efficient, George Kittle has been the best tight end in football, the offensive line has been cohesive and the complexities of Shanahan's scheme have been understood and implemented by an improving core.

The growing pains appear to be over. Their plus-133 point differential is best in the NFC (second is Minnesota at plus-76) and they trail only the Patriots (plus-172).

What are the 49ers good at?

The pass defense is the best in the league, allowing just 138.1 yards per game. That's due to improvements along all three levels of the defense. It starts with the defensive line, but the team has also seen significant boosts at linebacker in third-round draft pick Fred Warner's second season, and the addition of pugnacious veteran Kwon Alexander, who was lost for the year last Thursday with a torn pectoral. He'll be replaced by promising rookie Dre Greenlaw, a fifth-round pick who played well enough during training camp to win a starting job as a base linebacker.

The secondary has stabilized and improved significantly since last season with addition of former Broncos defensive coordinator Joe Woods as the passing game coordinator and defensive backs coach.

The 49ers in 2018 started eight different combinations of safeties and the cornerback spot opposite Richard Sherman was a turnstile throughout the year. This season, Sherman has improved as he's further removed from his 2017 Achilles tear, and youngsters Ahkello Witherspoon and Emmanuel Moseley have shown significant development from last season. Jimmie Ward and Jaquiski Tartt have stabilized the safety spots while Tarvarius Moore, a 2018 third-round pick, has shown flashes as a reserve.

What about the weaknesses?

This list isn't very long. But there are a couple things to keep an eye amid the best 49ers start since 1990.

The 49ers have allowed 596 rushing yards on 108 attempts over their last five games. That's a 5.5-yard average, which includes yielding 110 yards on 15 carries to Kenyan Drake in his first game with the Cardinals on Thursday, and 105 yards on 11 runs to budding star Christian McCaffrey four days earlier.

A question about the defense coming into the season revolved around their new “Wide 9” alignment with defensive ends lining up well outside the shoulder of opposing tackles. In essence, the alignment makes it easier to double team defensive tackles and allow offensive linemen easier paths to block inside linebackers.

The 49ers have outscored opponents 109-43 in the first half this season, which has led to opponents mostly abandoning the running game after falling behind early. To this point, the 49ers haven't had to play from behind, which means their issues defending the run haven't been problematic.

Additionally, the 49ers haven't had a very threatening receiving corps. That is until trading for veteran Emmanuel Sanders before last week's trading deadline. Sanders has been a quick study, with 11 catches on 14 targets for 137 yards and two short touchdowns in two games. Otherwise, San Francisco's top receiver has been rookie Deebo Samuel, who averaged just 32 yards per game. Kittle was easily the passing game's most effective target before Sanders' arrival.

Is the 49ers' success sustainable?

The discussion surrounding the 49ers has been about the viability of their start, given their weak opponents. In eight games they've played two quarterbacks with playoff victories (Jared Goff and Case Keenum), two backups (Mason Rudolph and Kyle Allen), two that have been benched (Andy Dalton and Keenum) and two former No. 1 draft picks in their first two seasons (Baker Mayfield and Kyler Murray).

It hasn't been a murderer's row of offenses during the first half of the season. Undoubtedly, the best performance was holding the Rams to seven points on the road Week 6, which was part of a string of four-straight games with 100 net passing yards allowed or fewer. Simply put, the 49ers have done what good teams are supposed to do against lackluster competition: dominate.

Any answers about San Francisco's defense should be answered over the second half of the schedule. Starting Monday, the 49ers will face three quarterbacks who have won Super Bowls (Russell Wilson, Aaron Rodgers and Drew Brees) an MVP candidate (Lamar Jackson) and two quarterbacks that have appeared in recent Super Bowls (Goff and Matt Ryan). We'll have a very good idea about exactly how good the defense is over the second half.