Rating NFL Quarterbacks

By Michael Gertz
Monday, June 20, 2016

Our Expected Points Added (EPA) statistics provide a unique insight toward why some NFL teams are better or worse than others, and in exactly what areas they excel. They have the benefit of added granularity beyond standard box score stats by untangling things like offense, defense, turnovers, and special teams, which all impact one another in the box score. The most consistent and predictive area of our EPA stats is passing offense. Because in the NFL quarterbacks are such a large component of passing efficiency, they are the one position that can actually be evaluated largely with stats alone

Quarterback EPA

EPA stats also measure the exact relative impact of each play. They can assign a point value to every play rather than having them remain in separate categories like yards, interceptions, and sacks. The table below gives a quarterback's team's expected points added per game on all called pass plays (completions, incompletions, scrambles, interceptions, and sacks) that didn't result in a lost fumble after a completion.

For the sake of simplicity, the figures are team values rather than specific to exactly which quarterback was involved in each play. A quarterback is given his team's season long figure only if he started at least 12 games in that season, so the figures are still very representative apart from rare scenarios like Mariota where a backup played a few games at an extremely different level of efficiency. All values are relative to the league average for that specific year, which has increased by just over 2 points per game over the last 7 seasons.

Team Pass EPA per Game
QB	2009	2010	2011	2012	2013	2014	2015	Avg
Peyton Manning	6.7	5.5		6.8	12.0	5.3		7.3
Aaron Rodgers	6.5	5.9	13.0	5.9		8.0	0.0	6.6
Drew Brees	7.1	4.2	11.1	6.0	6.6	4.8	5.1	6.4
Tom Brady	5.9	5.9	9.3	8.3	2.9	3.0	4.5	5.7
Tony Romo	4.2		4.1	3.3	2.5	5.5		3.9
Philip Rivers	8.5	6.6	3.6	-2.1	6.8	2.6	0.7	3.8
Kirk Cousins							3.5	3.5
Matt Ryan	1.7	4.1	3.7	6.6	2.3	1.9	1.9	3.2
Russell Wilson				2.8	2.9	1.5	4.9	3.0
Ben Roethlisberger	2.7	3.2	2.4	0.8	0.7	6.9	2.9	2.8
Andrew Luck				1.1	1.8	5.1		2.7
Matthew Stafford			4.3	0.9	1.9	0.4	1.0	1.7
Cam Newton			2.0	1.6	0.6	-0.3	2.3	1.2
Eli Manning	4.3	0.9	4.2	1.7	-5.5	1.2	1.2	1.1
Carson Palmer	-0.3	0.3		-0.6	-0.9		7.1	1.1
Jameis Winston							0.8	0.8
Joe Flacco	0.6	1.5	0.5	-0.2	-3.0	2.8		0.4
Colin Kaepernick					1.2	-0.5		0.4
Alex Smith			-0.8		0.5	0.5	-0.5	-0.1
Robert Griffin				3.2	-3.5			-0.2
Andy Dalton			-1.8	-1.5	1.2	-2.4	3.6	-0.2
Tyrod Taylor							-0.5	-0.5
Ryan Fitzpatrick		-3.7	-1.0	-1.6		-0.9	2.1	-1.0
Ryan Tannehill				-2.6	-2.5	0.0	-2.3	-1.9
Jay Cutler	-1.4	-2.7		-2.8		-1.6	-1.7	-2.0
Sam Bradford		-3.6		-1.3			-2.4	-2.4
Teddy Bridgewater						-3.5	-2.7	-3.1
Brian Hoyer						-3.3		-3.3
Marcus Mariota							-3.4	-3.4
Derek Carr						-6.7	-1.6	-4.2
Blake Bortles						-8.3	-0.4	-4.4
Brandon Weeden				-4.5				-4.5
Geno Smith					-5.8	-4.3		-5.1
Blaine Gabbert			-7.9					-7.9

Other Considerations

The table above represents a solid baseline for rating quarterbacks who have played several years in the NFL. The averages given include the last 7 years and are not meant to represent a QB's current quality, as it can change over time. Of course, there are other factors to consider that can impact a QB's EPA stats, and these factors will have a relatively greater impact on QBs with smaller sample sizes.

The main context to keep in mind when viewing these stats is what a QB's supporting cast was on offense. While the quarterback by far has the biggest impact of any player on a team's overall passing EPA, the quality of a team's receiving corps and blocking can still have a big impact as well.

The quality of teammates may affect some QBs more than others. Players like Philip Rivers and Eli Manning tend to play very well with good teammates but perhaps can't compensate as well for bad teammates like other QBs with good pocket awareness, scrambling ability, or a tendency to make quick throws who generally have more consistent marks from year to year.

A final consideration that pass EPA doesn't fully capture is a QB's rushing ability. While it does include scrambles, it doesn't include called QB runs. More importantly, it also doesn't include option plays where just the threat of the QB keeping the ball allows the RB to gain additional yardage. Our data indicates that teams with athletic QBs that make a point of having QB runs be a consistent threat can increase their rushing EPA by up to 2 points per game.

In the future, we hope to fully categorize the EPA data to account for who was the QB in each game to further inform our player ratings and team ratings model, rather than relying on season-long data for QBs that played at least 12 games as in the table above.