Nick Foles ranked 19th most impactful quarterback on weekly spreads

BetOnline has released every NFL starting quarterback's average effect on the weekly spread compared to their backups, and Jacksonville Jaguars quarterback Nick Foles landed in a somewhat expected spot.
The effect the quarterback has on the weekly point spreads is relative to the difference between the starter and his backup. For example, Patrick Mahomes affects the spread by -7 points.
This means the line would drop 7 points if Mahome's backup had to play. So since the Kansas City Chiefs are -3.5 point favorites against the Jaguars on Sunday, this means if Mahomes' backup was playing instead of him, the Jaguars would be -3.5 point favorites instead.
So by this logic, Foles ranks as the 19th most impactful starting quarterback on weekly spreads, according to Betonline. He has a value of -2.5, meaning the Jaguars would lose 2.5 points on any spread if Gardner Minshew was starting instead.
So, instead of being 3.5 point underdogs to the Chiefs in Jacksonville on Sunday, the Jaguars would be a 6 point underdogs if Minshew started. It is also worth taking into account these numbers are averages as there are different point values for when teams are home or away.
Incredible: @betonline_ag released the effect each starting QB has on the point spread (yes it's complicated; this is an average).
— Nick Veronica (@NickVeronica) September 3, 2019
Aaron Rodgers is the highest, the line would drop 7.5 pts if his backup had to play.
Eli Manning?
...
The #NYGiants would GET a point if he sat. pic.twitter.com/JVjSYnNvVU
Going off of this, spreads determine Foles is less impactful to games than quarterbacks like Dak Prescott, Matthew Stafford and Mitchell Trubisky. It would also make him as equally valuable as Kirk Cousins and Jimmy Garoppolo, but more valuable than Lamar Jackson, Jacoby Brissett and Jameis Winston.
This makes sense to a degree. Foles is likely more valuable than Trubisky in a real world sense, but it makes sense that oddsmakers are afraid to call him a definitive game-changer yet because, in their eyes, he has not earned that distinction as a 16-game starter yet.
What do you think? Do you think oddsmakers are too low on Foles, or just about right?

John Shipley has been covering the Jacksonville Jaguars as a beat reporter and publisher of Jaguar Report since 2019. Previously, he covered UCF's undefeated season as a beat reporter for NSM.Today, covered high school prep sports in Central Florida, and covered local sports and news for the Palatka Daily News. Follow John Shipley on Twitter at @_john_shipley.
Follow _john_shipley