Another Quarterback Aging Curve Post (Adjusted Net Yards Per Attempt Edition)

by Neil Paine on August 6, 2013

No, Peyton, you are #1.

Back in March, Chase wrote a post investigating how quarterbacks age, finding that they peak at age 29 (with a generalized peak from 26-30) in terms of value over average. Today, I thought I’d quickly look at how quarterbacks age in terms of their performance rate — specifically, their Adjusted Net Yards per Attempt (ANY/A). For newer readers, ANY/A is based on the following formula: (Passing Yards + 20 * Passing TDs – 45 * INTs – Sack Yards Lost) / (Pass Attempts + Sacks).

First, I need to introduce a way of adjusting ANY/A for era: Relative ANY/A. Relative ANY/A is simply equal to:

QB_ANY/A – LgAvg_ANY/A

The table below lists the 30 single-season leaders in Relative ANY/A since the merger. You won’t be too surprised to see the 2004 version of Peyton Manning at the top. That year, Manning averaged 9.8 ANY/A, while the league average was just 5.6 ANY/A. That means Manning gets a Relative ANY/A grade of +4.1 (with the difference due to rounding).

Search:

Rk	Player	Year	Age	Team	G	GS	Cmp	Att	Yds	TD	Int	Sk	SkYd	ANY/A	LgAvgANY/A	Rel_ANY/A
1.	Peyton Manning	2004	28	clt	16	16	336	497	4557	49	10	13	101	9.8	5.6	+4.1
2.	Dan Marino	1984	23	mia	16	16	362	564	5084	48	17	13	120	8.9	5.0	+3.9
3.	Roger Staubach	1971	29	dal	13	10	126	211	1882	15	4	23	175	7.8	3.9	+3.9
4.	Bert Jones	1976	25	clt	14	14	207	343	3104	24	9	29	284	7.8	4.1	+3.7
5.	Aaron Rodgers	2011	28	gnb	15	15	343	502	4643	45	6	36	219	9.4	5.9	+3.5
6.	Ken Stabler	1976	31	rai	12	12	194	291	2737	27	17	19	203	7.4	4.1	+3.4
7.	John Brodie	1970	35	sfo	14	14	223	378	2941	24	10	8	67	7.5	4.2	+3.4
8.	Tom Brady	2007	30	nwe	16	16	398	578	4806	50	8	21	128	8.9	5.5	+3.4
9.	Randall Cunningham	1998	35	min	15	14	259	425	3704	34	10	20	132	8.5	5.3	+3.2
10.	Steve Young	1992	31	sfo	16	16	268	402	3465	25	7	29	152	8.1	4.9	+3.2
11.	Mark Rypien	1991	29	was	16	16	249	421	3564	28	11	7	59	8.3	5.2	+3.2
12.	Kurt Warner	1999	28	ram	16	16	325	499	4353	41	13	29	201	8.3	5.2	+3.1
13.	Ken Stabler	1974	29	rai	14	13	178	310	2469	26	12	18	141	7.0	3.9	+3.1
14.	Steve Young	1991	30	sfo	11	10	180	279	2517	17	8	13	79	8.3	5.2	+3.1
15.	Joe Montana	1989	33	sfo	13	13	271	386	3521	26	8	33	198	8.3	5.2	+3.1
16.	Craig Morton	1970	27	dal	12	11	102	207	1819	15	7	20	166	7.2	4.2	+3.1
17.	Dan Fouts	1982	31	sdg	9	9	204	330	2883	17	11	12	94	7.7	4.8	+2.9
18.	Joe Montana	1984	28	sfo	16	15	279	432	3630	28	10	22	138	7.9	5.0	+2.9
19.	Ken Anderson	1975	26	cin	13	13	228	377	3169	21	11	32	247	7.0	4.0	+2.9
20.	Steve Young	1994	33	sfo	16	16	324	461	3969	35	10	31	163	8.2	5.4	+2.9
21.	Boomer Esiason	1988	27	cin	16	16	223	388	3572	28	14	30	245	7.8	5.0	+2.8
22.	Kurt Warner	2000	29	ram	11	11	235	347	3429	21	18	20	115	8.0	5.2	+2.8
23.	John Hadl	1973	33	ram	14	14	135	258	2008	22	11	17	126	6.6	3.9	+2.8
24.	Peyton Manning	2005	29	clt	16	16	305	453	3747	28	10	17	81	8.0	5.3	+2.7
25.	Drew Brees	2009	30	nor	15	15	363	514	4388	34	11	20	135	8.3	5.7	+2.7
26.	Philip Rivers	2009	28	sdg	16	16	317	486	4254	28	9	25	167	8.3	5.7	+2.7
27.	Steve McNair	2003	30	oti	14	14	250	400	3215	24	7	19	108	7.8	5.2	+2.6
28.	Brian Griese	2000	25	den	10	10	216	336	2688	19	4	17	139	7.8	5.2	+2.6
29.	Peyton Manning	2006	30	clt	16	16	362	557	4397	31	9	14	86	7.9	5.4	+2.5
30.	Tom Brady	2010	33	nwe	16	16	324	492	3900	36	4	25	175	8.2	5.7	+2.5

Using this, we can evaluate every quarterback’s season independently of era, and compute the year-to-year differences in Relative ANY/A at every age.

Taking every quarterback who had at least 15.1 dropbacks per game (which tends to correspond to the standard 14 attempts per team game) in back to back seasons, I fed the year-to-year Relative ANY/A deltas into a cubic regression and smoothed out an aging curve. (This is the same process I used to calculate an aging curve for basketball players for ESPN Insider last year.)

According to this methodology, here’s how a QB can expect his Relative ANY/A to change from year to year at each age:

From Age	To Age	Delta
20	21	+0.88
21	22	+0.66
22	23	+0.47
23	24	+0.32
24	25	+0.20
25	26	+0.10
26	27	+0.02
27	28	-0.04
28	29	-0.08
29	30	-0.11
30	31	-0.14
31	32	-0.15
32	33	-0.17
33	34	-0.19
34	35	-0.21
35	36	-0.24
36	37	-0.28
37	38	-0.33
38	39	-0.40
39	40	-0.50
40	41	-0.61
41	42	-0.76

Or in graphic form:

This would indicate that on average, quarterbacks peaks at age 27. To put the data in another light, if we created a passer who peaked at 8.0 ANY/A, and he perfectly followed this age curve, here is how his ANY/A would look each season:

One big caveat with this study: there’s probably a good deal of selection bias here, in the sense that only passers deemed to be good enough to keep playing will get a chance to put up 15.1 dropbacks/game the following year. Still, I think this provides a pretty good estimate of how much improvement/decline you can expect from a guy at a given age.

Armed with this aging curve, we can do a lot of cool things in subsequent posts, so stay tuned….

Tagged as: ANY/A, RANY/A

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