Creating Power Rankings

Just as a lark, I figured I'd try devising some power rankings using my model. The basic idea behind them is this: If every team played each other once at home, once at away, who would win the most?

I tested this idea on the 2006 teams after the end of the regular season. Using my adj. rush, adj. pass, sack, adj. 3rd down conv., and turnover data, I trained a linear regression predictor on all games before 2006. Then I used the model to predict the outcomes of all 992 possible games. I created 2 separate rankings: one based on the sum of margins of victory/defeat, one based on the expected winning percentage.

Rank	Team	Sum of Exp. Margins
1	PHI	4.2027
2	SD	4.1368
3	BAL	3.8437
4	JAX	3.2917
5	DAL	2.1643
6	CHI	2.1514
7	PIT	1.9942
8	NO	1.8954
9	IND	1.7482
10	NE	1.5237
11	MIN	1.1935
12	CAR	1.1847
13	ATL	0.94039
14	NYG	0.84285
15	MIA	0.82191
16	GB	0.71736
17	CIN	0.52797
18	DEN	0.33802
19	KC	0.29031
20	SF	-0.685
21	WAS	-1.0359
22	STL	-1.4769
23	NYJ	-1.5889
24	SEA	-2.0378
25	BUF	-2.3402
26	TEN	-2.4492
27	TB	-2.8237
28	ARI	-3.2092
29	DET	-3.6094
30	OAK	-3.7756
31	HOU	-3.8764
32	CLE	-4.9007

Rank	Exp. Win %	Team
1t	BAL	0.83871
1t	PHI	0.83871
3	SD	0.80645
4	JAX	0.72581
5t	CHI	0.66129
5t	NO	0.66129
7	NE	0.64516
8t	DAL	0.62903
8t	CAR	0.62903
10t	PIT	0.6129
10t	IND	0.6129
10t	MIN	0.6129
13t	MIA	0.59677
13t	ATL	0.59677
15	NYG	0.58065
16	GB	0.56452
17t	CIN	0.54839
17t	DEN	0.54839
17t	KC	0.54839
20t	STL	0.43548
20t	SF	0.43548
22t	NYJ	0.41935
22t	WAS	0.41935
24	SEA	0.33871
25	TEN	0.32258
26	BUF	0.27419
27t	OAK	0.19355
27t	ARI	0.19355
29t	CLE	0.17742
29t	HOU	0.17742
29t	DET	0.17742
29t	TB	0.17742

Looking at the bottom, it's about what you'd expect. Seattle, a playoff team, shows up at #24 in both rankings, but they were 8-8 in a weak division and suffered some losses due to injury and free agency. The Jets, another playoff team, show up at #23 and #22 respectively due to weak rushing offense and defense and average passing offense and defense. Seattle and the Jets were #25 and #19 respectively in Football Outsider's 2006 DVOA rankings. Philadelphia, despite a 10-6 record, shows up at #1 with a very strong offense (14.721% VOLA rushing, 20.58% passing unadj.). Jacksonville also obtains a very high ranking (#4) despite its record, a mediocre 8-8, thanks to well above average rush offense and defense. New England is a little low compared to DVOA (#10 and #7, #5) with average and below average YPA numbers but high sack and interception rates. The Super Bowl champion Colts are at #9 and #10 (DVOA #7) with 20.142% VOLA in pass offense and 26.09% VOLA in pass defense(!too high!) but -28.29% VOLA rush defense.

So overall, the rankings turn out very similar to the DVOA rankings with individual teams gaining or losing a couple spots. There are no major disparities, however, that I can see, except maybe Dallas showing up too high in the ranking by points. It would be interesting to calculate these rankings over the season and compare these with other rankings.

Figures and article corrected on 7/12/2007 after finding errors in some box scores.