LAS VEGAS — For most of the offseason, there was no reason to expect Andrew Luck to be anything other than fully healthy for Week 1. With that expectation, the Colts’ Week 1 matchup against the Chargers was set with a line of Chargers -3, meaning people saw those teams as basically even in strength when you account for home field. When the public learned Luck was still dealing with an injury in August, the line started to creep toward the Chargers, first to Chargers -3.5 basically everywhere in Vegas, then to Chargers -4 at many places.

With Luck announcing his retirement over the weekend, the Colts are set to move forward with Jacoby Brissett as their starting quarterback. When the news broke on Saturday, sportsbooks took the team’s Week 1 matchup against the Chargers off the board. The question for the books is: where should we reopen the line with Brissett locked in as the starter?

Circa appears to be one of the first Vegas books to hang a new line on the game, making the Chargers six point favorites at about 7 p.m. local time, per Vegas Insider. That number was quickly gone, and by 7:30 p.m. local time the line was at Chargers -7.5.

Right around that 7:30 p.m. line move at Circa, CG Technology posted their new line for the game, making the Chargers 9.5-point favorites. Smart bettors who were in position to take advantage had the chance to pounce, and within 90 minutes, the line had been moved down two points to Chargers -7.5.

Soon after CG Technology’s move to Chargers -7.5, Circa’s line dropped to Chargers -7. On Sunday morning, other books started to get into the action, with Westgate opening at Chargers -7 and Southpoint at Chargers -7.5.

I expect the line to settle at Chargers -7, because like many bettors, I have a QB injury adjustment ready to go in cases just like this. While the Luck news is an extreme case, injuries are going to be a part of every NFL season. If you want to be in position to bet on an advantageous line, you need to be ready to strike.

Every time a starting quarterback suffers an injury during an NFL season, bettors have to determine how much that loss will impact the team’s betting lines moving forward. I had a four-point drop-off from a healthy Andrew Luck to a healthy Jacoby Brissett, based largely on what I feel is untapped potential for the latter and the strength of the Colts’ roster overall. Indianapolis has a strong offensive line, and if you can give a young passer time to throw, you can still have success moving the ball even without a star passer like Luck.

Below, I’ve gone team by team and listed my adjustment for each potential injury, including what would happen if Brissett were to get hurt himself. Unlike with my home-field advantage data, this process is less scientific and more done by feel. If, for example, you have some reliable data that tells you why Marcus Mariota to Ryan Tannehill is actually a massive drop-off, feel free to lean on that and make your own adjustments accordingly. After the table, I’ll go division by division and give brief reasoning for each number.

Quarterback injury adjustments

AFC East

Bills: Matt Barkley played much better than anyone expected in a road start against the Jets last year, so even if Josh Allen takes a step forward in 2019, there won’t necessarily be a ton of separation between the two in this offense. Every week of good football Allen can bank will cause this adjustment to get bigger though.

Dolphins: Ryan Fitzpatrick is both a better and worse quarterback than Josh Rosen, and it’s difficult knowing which Fitzpatrick you’ll get from game to game. If it turns out Rosen is actually a bad quarterback, this adjustment will need to be larger, but I’m not ready to give up on him after one bad year in an awful situation.

Patriots: I might be underrating the drop-off from Tom Brady to Brian Hoyer at 4.5 points, but my logic is this: Hoyer is an accomplished veteran who has had plenty of time to get comfortable with Josh McDaniels’ system. And I find it hard to see a Bill Belichick-coached team being worse than average if Hoyer is at the helm.

Jets: This adjustment projects some growth in Sam Darnold in Year 2, and if he gets out to a hot start, we’ll need to bump it up by a point or two. Trevor Siemian got more than enough playing time in Denver for us to know he’s a backup-caliber quarterback.

AFC North

Ravens: It’s hard to calculate what the difference between Lamar Jackson and Robert Griffin would be, considering the team would have to scale back a large part of its rushing attack if Griffin takes the field. If rookie Trace McSorley can show anything with his arm, he might be a better backup option in this system.

Bengals: Andy Dalton deserves a lot of credit for being a solid NFL starter, but it remains to be seen how he’ll look in Zac Taylor’s offensive system. What we do know is that Taylor and his staff identified rookie Ryan Finley as a fit due to the fact they drafted him in April. If Cincinnati’s season goes as expected, Finley should get some starts by the end of the year.

Browns: Cleveland has a budding star in Baker Mayfield, but if he goes down, how much confidence do you have in Garret Gilbert or Drew Stanton? Gilbert has throw three passes since being taken in the 2014 draft, all in Week 17 last year, unless you want to count his AAF experience (I don’t). Stanton completed less than half his passes in each year from 2015-17.

Steelers: Pittsburgh could certainly wind up being fine with Josh Dobbs or Mason Rudolph under center, but Ben Roethlisberger has established himself as virtually irreplaceable. The Steelers also don’t have Le’Veon Bell and Antonio Brown around to boost the production of a backup quarterback if one is pressed into duty.

AFC South

Texans: AJ McCarron isn’t going to do everything Deshaun Watson can do in the Texans offense, but he has been successful in spot duty for the Bengals. Even having more faith in McCarron than past Houston backups, it’s a sizable drop-off from Watson to the QB2 here.

Colts: We saw essentially a full season with Jacoby Brissett under center in Indianapolis, and it was not great. But let’s consider the circumstances: Brissett was acquired on Sept. 2, 2017 and starting by Sept. 17. He’s also playing in a better offense surrounded by better talent in 2019 after getting sacked a league-high 52 times in 2017. Losing Andrew Luck is tough, but I don’t think it ends Indianapolis’ season. But having to turn to Walker or Chad Kelly would likely do just that.

Jaguars: Jacksonville finally got a legit quarterback (hopefully) in Nick Foles; can you imagine how devastating it would be mentally if he were to go down with a season-ending injury early in the year? That has to factor into my adjustment, but even if Foles does play poorly as a full-time starter, the Jaguars have zero established options behind him.

Titans: Ryan Tannehill is one of the most experienced backups in the league, starting 88 games since being drafted in 2012. He wasn’t particularly good, which is why he’s now a backup, but Marcus Mariota hasn’t exactly lit the league on fire since being a No. 2 overall pick in 2015. It sounds like Tannehill might have a shot to start, so if the coaches see this as a close matchup, our adjustment needs to take that into account.

AFC West

Broncos: Joe Flacco is probably one of the weaker starters in the league, but he’s playing in front of a raw rookie who likely isn’t ready to see the field, so there has to be some noticeable drop-off if Drew Lock is forced into action ahead of schedule.

Chiefs: Patrick Mahomes is the best quarterback in the league heading into 2019, and his backup, Chad Henne, hasn’t seen meaningful action since 2014. Henne also has more career interceptions than touchdowns and a 18-35 record as a starter. A Mahomes injury would be devastating, even with Andy Reid calling the shots.

Chargers: Worse quarterbacks than Philip Rivers see a larger adjustment if the team has to go to the backup, but that’s because the Chargers have one of the league’s better backups in Tyrod Taylor, who took the Bills — the Bills! — to the playoffs just two years ago.

Raiders: Mike Glennon is battling Nathan Peterman for the backup job in Oakland, and if he can’t beat out a guy who has thrown an interceptions in 9.2 percent of his career attempts, it’s a problem. The Raiders would easily have the worst power rating in the league if Derek Carr gets hurt.

NFC East

Cowboys: No backup situation is worse than the one in Dallas, so maybe go ahead and pay Dak Prescott, Cowboys brass. The Cooper Rush vs. Mike White battle leaves Prescott tied for the second-biggest adjustment in an injury scenario in the league.

Giants: Some would argue Daniel Jones is already a better quarterback than Eli Manning, but let’s not buy in too much to a few preseason throws. Manning’s familiarity in the offense and years of experience have to count for something, but his decline in talent is apparent, and it’s certainly possible Jones taking over ahead of schedule would be a net positive.

Eagles: Maybe no backup job in the league gets more visibility than the one in Philadelphia, where Carson Wentz has been unable to finish the season in each of the last two years. Nick Foles isn’t around to save the day anymore, but Josh McCown had a fine statistical season in 2017 and could at least do a serviceable job over a short period.

Redskins: Both Case Keenum and Dwayne Haskins are new to the Washington offense, and while Keenum’s NFL experience earned him the nod from Jay Gruden at the beginning of the year, Haskins’ clear edge in potential could cause him to earn the top job at anytime.

NFC North

Bears: Mitchell Trubisky has plenty of potential that has yet to be realized, Chase Daniel completed nearly 70 percent of his 76 passes in limited duty last year. At this point, there isn’t as much separation between the two in terms of setting a betting line, but Trubisky could certainly change that with a breakout season.

Lions: Matthew Stafford is as reliable as they come, and while he’s never won a playoff game, he’s finished with a winning record in half of his last eight seasons. The Lions’ backup situation is up in the air after Tom Savage suffered a concussion, but none of the options are all that appealing unless David Fales has hidden upside.

Packers: Aaron Rodgers is still one of the best quarterbacks in the league when healthy, and we saw in 2017 just how big his loss could be. DeShone Kizer went 0-15 as Browns starter in 2017, but no one was having success in that situation, especially not a raw 21-year-old. It’s possible Kizer has untapped potential; he certainly isn’t lacking in confidence.

Vikings: Kirk Cousins is a quality starter, if not a star, but the Vikings might not completely tank with Sean Mannion or Kyle Sloter under center. After all, this team turned Case Keenum into a legit MVP candidate just two years ago.

NFC South

Falcons: Matt Schaub seems to have one foot out the door after a career that featured one season where he averaged nearly 300 yards a game and another where he went 12-4 and won a playoff game. This isn’t 2012, so if Matt Ryan gets hurt, the Falcons are probably in more trouble than they were last year with all the defensive injuries combined.

Panthers: It was time for Cam Newton to sit down last year after dealing with his shoulder injury, but after an offseason of healing, he’s back to being one of the most valuable quarterbacks in the league. If Will Grier can play well enough to win the job over Taylor Heinicke, I’d have a little more trust in the Panthers if Newton is hurt again.

Saints: Drew Brees is in the twilight of his career, but all he did last year was complete 74.4 percent of his passes while going 13-2 as a starter. The reason this adjustment isn’t nearly as big as with other top quarterbacks is that Teddy Bridgewater is maybe the best backup in the league, despite what he showed in spot duty in Week 17.

Buccaneers: Last year Ryan Fitzpatrick and Jameis Winston showed at times it didn’t matter who the starter was. This year Blaine Gabbert is the backup. An injury to Winston would be devastating, and the only reason I’m not giving him a full touchdown over Gabbert is that we don’t know what to expect from him in this critical contract year.

NFC West

Cardinals: I wanted to give this team a larger adjustment if Kyler Murray goes down, but we just don’t know what to expect from the rookie out the gate. He’s a good bit better than Brett Hundley on talent alone, and if he hits the ground running, go ahead and bump this number up a couple points.

Rams: I’m not here to trash Jared Goff, nor do I think Blake Bortles has some hidden level of greatness after winning no more than five games in four of his five seasons. This relatively small adjustment has more to do with Sean McVay, who would certainly put Bortles in the best situation to succeed in his scheme. Trust in McVay more than Bortles.

Seahawks: Geno Smith is a backup with experience, but no one is going to be a capable fill-in for a quarterback as good as Russell Wilson. There’s a chance Paxton Lynch can win the job and show enough to at least give this team a fighting chance against non-playoff caliber teams.

49ers: Nick Mullens came out of nowhere and flashed in his eight starts as a rookie, completing 64.2 percent of his passes and averaging nearly 285 passing yards a game. Like with the Rams, this relatively small adjustment from Jimmy Garoppolo is about Kyle Shanahan’s ability to get the most out of his quarterbacks.