It’s a situation every sports bettor has faced before: You’re ready to place a bet on an NFL game, but the starting quarterback is questionable and you’re waiting to see if he can play.
Just how good is that backup QB from the school you’ve never heard of? Is the starter worth a field goal more against the spread? A touchdown more?
Knowing the point spread difference between a starting QB and a backup can immensely help bettors recognize value bets before the game if a QB change is made
As casual sports bettors’ knowledge has grown with expanded legalization, it’s more widely known that only a starting QB injury is going to significantly move the point spread for an NFL game
— with rare exceptions for a few skill players like Justin Jefferson or Tyreek Hill.
When a QB change is made before the game, how do oddsmakers determine the adjustment to the point spread?
It’s a nuanced answer in every case, and reliant on a variety of factors, including:
Aaron Rodgers was No. 1, a full eight points better ATS than his backup (DeShone Kizer).
Patrick Mahomes was in the second tier (+5 points ATS over Chad Henne). And Eli Manning was only 0.5 points better than backup Alex Tanney. Ouch, Eli.
The next year at ESPN, I repeated the exercise, using Salmons and Jeff Davis (then a director of trading at Caesars, now assistant sportsbook manager at Circa Sports).
Rodgers again was atop the rankings, worth 9.75 points more against the spread than backup Tim Boyle.
But in order to get a true picture of how oddsmakers think, I went much bigger this year:
I asked eight oddsmakers around the U.S. to give me the difference in the point spread if the starter and backup were playing at home against a league-average team,
and both players were fully healthy. I then took those eight values for each NFL team starter-backup pairing, averaged them together and ranked them.
The Elite QBs The Established Starters (and Justin Fields) The Veterans and Question Marks The Rookies The Arizona Cardinals