At the start of every NFL season, each team have the same 0-0 record. Combined with surprise trades, NFL draftees, free agency signings, shocking retirements and injuries, September signals the start of something new for all.

It has happened time again — a dark horse seemingly comes out of nowhere and has made a deep impression on that. Remember the 1988 Cincinnati Bengals that went to the Super Bowl, but were 4-12 the year before?

What about the 2008 Miami Dolphins who made it to the playoffs, even though they won just one game in 2007? Of course, the best example is Kurt Warner and the 1999 St Louis Rams, who won the Super Bowl that year, despite being 4-12 a season earlier.

Many eyes will be focused on the Cleveland Browns and Oakland Raiders this year, especially with the addition of Antonio Brown and Odell Beckham Jr. But what other teams have the potential to go from zero to hero?

Here we break down three teams that could surprise us all during the 2019 season.

San Francisco 49ers

Starting quarterback Jimmy Garoppolo is back, Jerick McKinnon has also returned, running back Tevin Coleman now is with the team and San Francisco drafted defensive end Nick Bosa with the second overall pick. Not to mention, George Kittle might be the best tight end in the league now the Rob Gronkowski has retired.

A lot of the 49ers' problems in their shoddy 2018 season (which saw them finish 4-12) were because of injuries. Garoppolo tore his anterior cruciate ligament in week three, meaning backups C.J. Beathard and Nick Mullins had to take over for the rest of the year. McKinnon's knee gave him issues all last season and he is still recovering, but the depth with Coleman and Matt Breida gives the Niners more options.

Garoppolo struggled in his first preseason game but was able to step up and help San Francisco defeat the Kansas City Chiefs during its second preseason game. Garoppolo said playing at Arrowhead Stadium, where he tore his ACL last year, helped shake off any apprehension.

"A lot has happened in the year since then," Garoppolo said. "I thought it would be good to go back there just to remember everything that I've gone through."

On the other side of the ball, Bosa will have a helping hand from Dee Ford, who was traded from the Chiefs in the offseason after a 13-sack 2018 campaign.

As long as everyone stays healthy, the 49ers have all the pieces to at least win their division.

New York Jets

A far cry from their Super Bowl victory half a century ago, the Jets finished last season with a 4-12 record. New quarterback Sam Darnold looked like a shaky high schooler starting for the first time, the offense was sluggish and their third-down conversion rate was abysmal (32.24 per cent). 

But things have changed on the offensive side for New York. Running back Le'Veon Bell signed a four-year, $52million deal with the team and has had a quiet and drama-free offseason with the Jets. Bell also seemed to have helped Darnold gain some confidence and has heaped praise on the young quarterback.

"Sam has all the intangibles, he has the mindset. You can see him — he's a competitor. Every day in practice he literally wants to get better. It's hard to ... it's hard to describe someone that's like that because I'm like that," Bell said during the preseason.

"A lot of people go to practice and you're just practicing. They call a play and you run the play. When they call a play for me, I'm trying to work myself and I'm trying to like really get better at it. And I can see that in Sam. When he makes a throw he doesn't really like, I can see that in his face, 'I could've thrown that better.' You've got to love that about him because he literally wants to be perfect. He reminds me a lot of myself in that aspect."

Meanwhile, Ty Montgomery also was signed to a one-year $805,000 contract. Montgomery especially is intriguing, since he can take on the dual role of tailback and receiver. First-year Jets head coach Adam Gase said he was shocked Montgomery had not been claimed off waivers after the Green Bay Packers released him and envisions him being the perfect complement to Bell.

Montgomery later added that he and Bell work well together, making them an efficient and top-notch duo.

"I think we complement each other," Montgomery said. "I'm more of a receiver that's become a back and he's a back that's sort of become a receiver. Us being on the field together, we can line up anywhere. We can do anything. When he comes off, I come on. My mindset, the way I'm wired right now, nothing's going to change, nothing should change. Our offense should be just as efficient."

Indianapolis Colts

No Andrew Luck? No problem. The quarterback's surprise retirement at the age of 29 could have sent other teams into a tailspin, but the Colts have played without Luck before, although that result was not spectacular. In recent seasons, Luck has dealt with various injuries, and Jacoby Brissett has stepped up.

Colts head coach Frank Reich said Indianapolis are in "good hands" with Brissett, even though he has a 4-11 record with the team when starting. 

"You can just feel his presence in the huddle and on the field," Reich said. "The confidence that he's had, the chemistry with his receivers. We all know Andrew and T.Y. [Hilton] had a unique chemistry and connection. I can feel that developing. That's been very important that Jacoby has taken all those reps."

Brissett had been taking the majority of first-team reps during training camp and working with Hilton, Pro Bowl tight ends Eric Ebron and Jack Doyle, and running back Marlon Mack, who nearly had a 1,000-yard season last year, despite missing five games. 

The stage is set for Brissett to succeed. As long as the offensive line — which includes first-round picks Anthony Castonzo, Ryan Kelly and Quenton Nelson — stays strong, Brissett and the Colts still have the chance to claim an AFC South title.