This week I’m excited to introduce a new data set into my quarterback rankings, courtesy of Pro Football Focus. I’d like to give a helmet knock to our good buddy Bryan Frye for working out some details behind the scenes to make this possible. ^[1]Note from Bryan: all I did was ask.

From this point forward, I will be using two metrics to rate quarterbacks: QBR and PFF offensive grades. This makes me giddy because both systems attempt to isolate the QB’s contribution from that of his teammates. That’s a significant step up from ANY/A, DYAR, and EPA which simply assign team offensive statistics to the QB taking the snaps. I can live with that for historical comparisons where we don’t have anything better, but in today’s world of robust data there’s no reason to settle for such a high degree of entanglement.

As neither QBR nor PFF grades account for workload, I needed to make an adjustment to prevent low usage QB’s from hogging the top of the rankings. After experimenting with a few ideas I settled on adding a z-score for play count (based on qualifiers only) and giving it half weight compared to the z-scores for the two metrics. It’s not perfect but it gets the job done without too many arbitrary decisions.

Let’s see how the new system looks for week 12:

#	QB Week 12	Plays	PFF	QBR	zPlays	zPFF	zQBR	zAvg
1	Aaron Rodgers	48	85.8	64.6	0.93	1.86	0.91	1.29
2	Joe Burrow	28	91.9	76.6	-1.38	2.34	1.48	1.25
3	Carson Wentz	53	79.6	61.4	1.50	1.38	0.76	1.16
4	Josh Allen	41	78.0	75.6	0.12	1.25	1.44	1.10
5	Derek Carr	50	64.5	78.8	1.16	0.20	1.59	0.95
6	Dak Prescott	54	74.2	46.5	1.62	0.95	0.05	0.73
7	Teddy Bridgewater	21	71.0	84.5	-2.19	0.70	1.86	0.59
8	Justin Herbert	58	55.7	59.4	2.08	-0.49	0.67	0.49
9	Andy Dalton	44	70.6	50.3	0.47	0.67	0.23	0.46
10	Tom Brady	41	73.7	42.7	0.12	0.92	-0.13	0.34
11	Jared Goff	32	67.7	60.8	-0.92	0.45	0.73	0.29
12	Taylor Heinicke	43	66.2	49.8	0.35	0.33	0.21	0.29
13	Daniel Jones	42	66.2	47.2	0.23	0.33	0.09	0.21
14	Jimmy Garoppolo	33	69.2	52.4	-0.80	0.56	0.33	0.20
15	Mac Jones	37	51.9	72.9	-0.34	-0.79	1.31	0.14
16	Tua Tagovailoa	39	61.1	47.1	-0.11	-0.07	0.08	-0.02
17	Trevor Lawrence	51	65.4	23.6	1.27	0.27	-1.04	-0.05
18	Russell Wilson	37	57.5	53.5	-0.34	-0.35	0.39	-0.05
19	Matthew Stafford	42	58.8	45.0	0.23	-0.25	-0.02	-0.06
20	Baker Mayfield	42	49.2	45.1	0.23	-1.00	-0.01	-0.36
21	Kirk Cousins	36	57.9	32.8	-0.46	-0.32	-0.60	-0.46
22	Tyrod Taylor	34	62.5	22.1	-0.69	0.04	-1.11	-0.56
23	Ben Roethlisberger	45	50.0	28.3	0.58	-0.94	-0.81	-0.58
24	Ryan Tannehill	29	54.8	37.6	-1.26	-0.56	-0.37	-0.63
25	Jalen Hurts	39	56.3	17.3	-0.11	-0.44	-1.33	-0.73
26	Lamar Jackson	51	41.7	25.0	1.27	-1.58	-0.97	-0.77
27	Matt Ryan	35	45.3	31.3	-0.57	-1.30	-0.67	-0.90
28	Trevor Siemian	36	50.8	14.2	-0.46	-0.87	-1.48	-1.03
29	Zach Wilson	30	44.1	9.8	-1.15	-1.40	-1.69	-1.46
30	Cam Newton	28	37.6	5.4	-1.38	-1.90	-1.90	-1.80

All things considered I think this passes the smell test. There are few instances in which PFF and QBR disagree sharply; the most notable is in regard to Derek Carr‘s Thanksgiving game in Dallas. QBR gives Carr credit for drawing four interference flags for 91 yards, all on third down. The PFF graders apparently weren’t as impressed by those throws. The crediting of quarterbacks for drawing penalties is a gray area that has no right answer, thus I’m glad we have representation on both sides of the debate.

Justin Herbert also sparked major disagreement between the metrics, with QBR liking his performance in Denver far more than PFF does. This one surprises me a bit considering Herbert threw a pick-six on a pass that bounced off his receiver’s hands. Normally PFF will absolve the QB of any wrongdoing on such plays while QBR will only give him a partial break.

One player PFF favored this week was Trevor Lawrence. His QBR was terrible to match his box score numbers but he actually graded above average against Atlanta. I didn’t see much of that game (who did?) so I can’t venture a guess as to why he graded relatively well. The Jags are a dysfunctional mess so it’s not hard to imagine that Lawrence’s teammates may have wasted some of his good plays.

Now let’s check out the season rankings:

#	QB 2021 Season	Plays	PFF	QBR	zPlays	zPFF	zQBR	zAvg	Diff
1	Tom Brady	511	91.5	63.6	1.00	1.75	1.21	1.38	0.54
2	Justin Herbert	534	85.8	65.9	1.26	1.17	1.40	1.28	0.23
3	Kirk Cousins	466	88.5	57.0	0.48	1.44	0.64	0.93	0.80
4	Josh Allen	522	82.0	60.6	1.12	0.78	0.95	0.92	0.17
5	Aaron Rodgers	432	82.7	64.9	0.09	0.85	1.32	0.89	0.47
6	Kyler Murray	336	85.6	63.5	-1.00	1.15	1.20	0.74	0.05
7	Matthew Stafford	457	76.2	65.8	0.38	0.19	1.39	0.71	1.21
8	Derek Carr	496	79.1	57.2	0.82	0.48	0.66	0.62	0.18
9	Ryan Tannehill	494	81.4	53.4	0.80	0.72	0.34	0.58	0.38
10	Mac Jones	460	83.9	52.6	0.41	0.97	0.27	0.58	0.71
11	Dak Prescott	460	84.4	50.6	0.41	1.02	0.10	0.53	0.93
12	Joe Burrow	413	86.2	51.3	-0.12	1.21	0.16	0.52	1.05
13	Patrick Mahomes	545	73.7	57.4	1.38	-0.07	0.68	0.52	0.75
14	Jalen Hurts	514	80.0	48.0	1.03	0.57	-0.12	0.39	0.70
15	Carson Wentz	490	72.3	56.7	0.76	-0.21	0.62	0.31	0.83
16	Matt Ryan	450	78.0	50.5	0.30	0.37	0.09	0.24	0.28
17	Lamar Jackson	508	73.5	51.1	0.96	-0.09	0.14	0.21	0.23
18	Teddy Bridgewater	415	78.7	50.1	-0.10	0.44	0.05	0.18	0.39
19	Jimmy Garoppolo	338	72.3	58.6	-0.98	-0.21	0.78	0.03	0.99
20	Tua Tagovailoa	283	73.5	57.7	-1.60	-0.09	0.70	-0.08	0.79
21	Jacoby Brissett	278	76.0	50.5	-1.66	0.17	0.09	-0.23	0.08
22	Daniel Jones	472	71.6	40.9	0.55	-0.28	-0.73	-0.30	0.45
23	Taylor Heinicke	454	64.8	48.8	0.35	-0.98	-0.06	-0.34	0.92
24	Russell Wilson	282	73.9	46.2	-1.62	-0.05	-0.28	-0.45	0.23
25	Baker Mayfield	389	65.3	37.9	-0.40	-0.93	-0.98	-0.84	0.06
26	Ben Roethlisberger	444	56.4	43.1	0.23	-1.84	-0.54	-0.91	1.30
27	Trevor Lawrence	504	59.8	33.9	0.92	-1.49	-1.33	-0.94	0.16
28	Sam Darnold	381	62.6	35.6	-0.49	-1.20	-1.18	-1.05	0.02
29	Jared Goff	433	60.6	29.3	0.11	-1.41	-1.72	-1.23	0.31
30	Justin Fields	299	64.2	25.9	-1.42	-1.04	-2.01	-1.50	0.97
31	Davis Mills	252	59.3	30.5	-1.96	-1.54	-1.62	-1.65	0.07
32	Zach Wilson	247	56.3	23.5	-2.02	-1.85	-2.21	-2.03	0.36

Well, swapping out EPA for PFF grades definitely shuffled the top of the leaderboard. Tom Brady and Kirk Cousins (yes, the guy I dissed last week) rise to first and third place on the strength of their PFF evaluations. Matthew Stafford tumbles way down because PFF grades him as barely above average in spite of his still strong QBR and box score stats. As someone who long believed that Sean McVay’s scheme carried Jared Goff, I fully support the notion that the scheme is also making Stafford look better than he really is.

To highlight the contrast between PFF and QBR I added the ‘Diff’ column; this is the absolute value difference between the z-scores for the two metrics. Sort by Diff and you’ll see which QB generates the biggest disagreement. It turns out that Ben Roethlisberger divides the metrics even more strongly than Stafford does. QBR sees Big Ben as merely below average while PFF views him as being washed beyond repair.

I hope you guys enjoy the new rankings. Comments and questions are always encouraged!