The NFL Live crew examines why Andrew Luck, Ryan Tannehill and Case Keenum will have the biggest impact of QBs in new situations this season. (1:34)

Hey, who's the new guy? In Week 1 in the NFL, there was a pretty good chance it was the starting quarterback.

A total of 15 NFL teams had different Week 1 starting quarterbacks this year than they had in 2017. How unusual is that? Only once in the Super Bowl era has that number been higher -- in 1999, when 16 teams had different Week 1 starters than they had in 1998.

Amazingly, of this year's 15 new starters, only one was a rookie -- the Jets' Sam Darnold. The turnover at quarterback over the past 12 months has been historic even for a league that lives with constant churn at the position, and history tells us things are likely to remain unsettled in many of these places.

So we thought we'd take a look at the 15 new Week 1 quarterback starters and their situations, just to see how this all happened and how likely each new guy will stick.

Kirk Cousins and Jimmy Garoppolo were part of the turnover wave among starting quarterbacks in the past year. Brace Hemmelgarn/USA TODAY Sports

How he got here: After Washington moved on to Alex Smith, Cousins made it to the free-agent market and signed a fully guaranteed three-year, $84 million contract with the Vikings.

Expectations: HIGH . The Vikings have their sights set on this year's Super Bowl, and they and their fans are hoping Cousins was the missing piece. He's got as much pressure on him as any quarterback in the entire league.

Job security outlook: Guaranteed means guaranteed. As long as Cousins stays healthy, it's impossible to imagine a scenario in which he gets benched. And even if they hypothetically wanted to get rid of him, who's going to trade for that contract?

Sam Darnold, New York Jets

How he got here: The Jets traded three second-round picks to the Colts to move up from No. 6 to No. 3 in the draft and selected the former USC quarterback. He then beat out 2017 starter Josh McCown and Teddy Bridgewater (who got traded) for the starting job in camp.

Expectations: HIGH . The Jets have been looking for a franchise quarterback since Joe Namath left town. Fans are desperate for Darnold to live up to his draft position and Monday's dazzling debut (16-for-21, 198 yards, 2 TDs, 1 INT).

Job security outlook: They could always go back to McCown, but the veteran backup seems to relish the mentor role. Darnold would have to struggle mightily to see the bench this year.

How he got here: The 49ers traded a second-round pick to the Patriots for Garoppolo at last year's trade deadline. After a month spent learning the offense, he became the starter in early December and opened eyes around the league by leading the Niners to a 5-0 record in their final five games.

Expectations: HIGH . Going 5-0 in December can't help but raise expectations for the following season, and the Niners hope and believe Garoppolo is the long-term answer for them at the position. A tough opening loss to the Vikings and their tough defense puts a bit of a damper on things, but the expectation is that he will bounce back.

Job security outlook: The Niners signed Garoppolo to a five-year, $137.5 million contract this offseason, guaranteeing $48.7 million, including $7.5 million of his $17.2 million 2019 salary. They theoretically could cut him after this season, but they'll have paid him almost $50 million for just one year's work. This job is his for at least two years, and -- they hope -- much longer.

How he got here: After a year of lost QB play bouncing from Trevor Siemian to Paxton Lynch to Brock Osweiler, the Broncos signed Keenum to a two-year, $36 million free-agent contract with $25 million guaranteed.

Expectations: HIGH . By comparison to what came before, and based on his surprise breakout 2017 season as a Viking, Keenum is seen by Broncos coaches and fans as some sort of low-key savior.

Job security outlook: Guaranteeing $25 million means he's the guy for this year, at least. Only $7 million of his $18 million 2019 salary is guaranteed, so if he's a flop in 2018, the Broncos can move on. At this point, though, only Chad Kelly is a candidate to be the long-term solution.

How he got here: Luck missed the entire 2017 season while recovering from shoulder surgery but is healthy now and took the job back from last year's fill-in, Jacoby Brissett.

Expectations: HIGH . Luck was one of the best quarterbacks in the league during the healthy early portion of his career. The Colts believe their offensive line is better than any he has ever had before.

Job security outlook: Brissett is no threat, and Luck is signed through 2021.