There is a certain mystery about how bookmakers set lines for NFL games that varies from sportsbook to sportsbook. There is no position more important to a line than a team's starting quarterback.
For oddsmakers, it is a constant challenge to keep track of injury reports, coaches' news conferences, Twitter and more to figure out starting QBs each week and adjust spreads accordingly.
When a QB change is made, how do oddsmakers adjust? How much is each quarterback worth against the point spread?
The answer to this question is nuanced and involves a quarterback's overall talent level, how much better he is than his backup and where the difference between QBs lands with respect to key numbers (three, four, seven, etc.) when making a point spread.
When my colleague Doug Kezirian did this piece last season, the top QBs against the spread were Aaron Rodgers (with DeShone Kizer as his backup) and Tom Brady (Brian Hoyer), both worth eight points.
Rodgers has now taken that crown, as he's worth nearly 10 points against the number, according to Vegas oddsmakers.
"I think bookmakers learned their lesson in 2013, when Rodgers got hurt and was replaced by Scott Tolzien," Jeff Davis, director of trading at Caesars Sportsbook, told ESPN. "The number adjusted by roughly seven points, and Green Bay lost at home by two touchdowns. This offense just isn't remotely the same without him."
Brady is next on the list, worth nearly nine points against the number, followed by MVP front-runners Russell Wilson (8 points) and Lamar Jackson (7.5).
Jackson has been the biggest riser this season in the eyes of bookmakers.
"From that first half in the playoffs against the Chargers to now, I wouldn't have thought [his current playing level] was possible," Ed Salmons, vice president of risk at the SuperBook at the Westgate Las Vegas, told ESPN. "It shows you how brilliant John Harbaugh is, molding the offense around the players he has."
Jackson is the current MVP odds leader at +120 at Caesars Sportsbook, followed by Wilson at +200, Patrick Mahomes at +800 and Deshaun Watson at +900. Rodgers has 18-1 odds, and Brady is at 30-1.
One of the biggest fallers? None other than Chicago Bears QB Mitchell Trubisky, who went from having the most MVP bets on him in the preseason to being benched for Chase Daniel. Bookmakers currently see him as worth only a half-point more than Daniel; last season, it was closer to a field goal difference.
"Both have shown little to no ability in leading an offense to any semblance of sustained success," Davis said. "We don't feel there is much of a difference between them."
There was consensus that two teams were actually worse with their current starting QBs than their backups. It is no surprise that those teams are the Washington Redskins (Dwayne Haskins over Case Keenum) and Cincinnati Bengals (Ryan Finley over Andy Dalton).
The other quarterback situation to monitor is in Pittsburgh, where bookmakers thought Mason Rudolph was worth roughly three points more than Devlin "Duck" Hodges.
Perhaps the most surprising evaluation was San Francisco 49ers QB Jimmy Garoppolo, whom oddmakers saw as worth only two points more than Nick Mullens.
"Mullens gave a pretty good account of himself over the last month of last season," Davis said. "Garoppolo isn't the reason the 49ers are where they are right now. He throws too many INTs and is no better than a 'league average' quarterback."
Here is how much every starting NFL QB is worth against the spread: