A comparative look at Cal's defense

There's been a fair amount of discussion recently regarding Cal's defense, including much citing of statistics, and while the discussions have been very interesting, I feel like we might be approaching some of these statistics in the wrong way. The usage of statistics seems to fall mostly into the following two categories, both of which are problematic:

1. Looking at statistics in a vacuum - e.g. "Wazzou passed for 350 yards against us, so our secondary is doing badly".
--> Hypothetically, Wazzou could be passing for 400+ yards against everyone else. We know that this isn't the case, but the point is that the frame of reference is somewhat arbitrary/subjective.

2. Looking at statistics in terms of Pac-10 ranking - e.g. "Cal is second in the Pac-10 in points per game".
--> Hypothetically, the next eight Pac-10 teams could just have really terrible offenses. Also, this fails to account at all for strength of schedule, which is definitely relevant to a team's statistics.

For the purposes of this fanpost, I decided to use a slightly different method of evaluating Cal's defense: comparing opponents' performance against us to their average performance this season. In other words, instead of looking at whether our defense performed better or worse than average against each opponent, I'm looking at whether our defense made opposing offenses perform better or worse than they usually do. This isn't a particularly original idea, and it has its own flaws (again, it doesn't take schedule into account at all), but it has the virtue of demonstrating in what manner opposing offenses are able to perform well against us, compared to their other performances.

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Data is from ESPN and cfbstats.com. Note that a few of the categories do not include last week's games. The categories are also somewhat arbitrary. My goal is to get a sense of whether any statistics in particular jump out at us. If there is interest, I can put together a more detailed version of this post later on.

The index below is the ratio of how an opposing offense performed against Cal to how they normally perform, i.e. a higher index means they did better against us than they usually do; a lower index means that they did worse against us than they usually do.

 

MARYLAND	Average	vs. Cal	Index
Points	22.83	13	0.57
Total YPG	328.83	303	0.92
Rushing YPG	90.43	136	1.5
Rushing YPA	2.73	3.16	1.16
Passing YPG	237.97	167	0.7
Passing YPA	6.97	5.6	0.8
Completion %	59.1	56.7	0.96
Passer Rating	124.42	103.43	0.83
First Downs	16.2	17	1.05
3rd Down %	0.4	0.24	0.6
Red Zone %	0.87	1	1.15
Turnover Margin	-1.43	-2	x

(This game was the reverse of all the others in terms of rushing/passing indices, but Maryland is a horrible team, so I wouldn't read too much into it.)

 

MINNESOTA	Average	vs. Cal	Index
Points	23.7	21	0.89
Total YPG	322.09	270	0.84
Rushing YPG	112.38	37	0.33
Rushing YPA	3.76	1.76	0.47
Passing YPG	209.71	233	1.11
Passing YPA	6.68	6.9	1.03
Completion %	53.79	64.7	1.2
Passer Rating	110.98	133.75	1.21
First Downs	15.24	14	0.92
3rd Down %	34.86	33.33	0.96
Red Zone %	0.83	1	1.2
Turnover Margin	-0.19	-3	x

OREGON	Average	vs. Cal	Index
Points	34.69	42	1.21
Total YPG	380.91	524	1.38
Rushing YPG	232.91	236	1.01
Rushing YPA	4.92	4.54	0.92
Passing YPG	148	288	1.95
Passing YPA	6.49	9	1.39
Completion %	57.99	78.1	1.35
Passer Rating	117.79	184.67	1.57
First Downs	19.14	26	1.36
3rd Down %	31.05	46.67	1.5
Red Zone %	0.91	1	1.1
Turnover Margin	0.95	-1	x

(This is one of those cases where the stats don't show how horrible the beat-down was...also Oregon has been beating a lot of other teams down as well, which probably explains the relatively low indices.)

USC	Average	vs. Cal	Index
Points	30	30	1
Total YPG	421.91	457	1.08
Rushing YPG	193.43	174	0.9
Rushing YPA	5.63	4.14	0.74
Passing YPG	228.49	283	1.24
Passing YPA	9.13	8.1	0.89
Completion %	61.1	57.1	0.93
Passer Rating	147.56	119.35	0.81
First Downs	18.63	20	1.07
3rd Down %	32.8	40	1.22
Red Zone %	87.3	100	1.15
Turnover Margin	-0.63	1	x

 

UCLA	Average	vs. Cal	Index
Points	19.03	26	1.37
Total YPG	285.6	448	1.57
Rushing YPG	97	137	1.41
Rushing YPA	3.29	5.27	1.6
Passing YPG	188.6	311	1.65
Passing YPA	5.57	7.4	1.33
Completion %	54.11	50	0.92
Passer Rating	100.86	107.44	1.07
First Downs	15.86	17	1.07
3rd Down %	29.25	31.25	1.07
Red Zone %	80.95	100	1.24
Turnover Margin	0.78	-2	x

 

WSU	Average	vs. Cal	Index
Points	14.83	17	1.15
Total YPG	260.34	440	1.69
Rushing YPG	79.34	55	0.69
Rushing YPA	2.27	1.96	0.86
Passing YPG	181	385	2.13
Passing YPA	5.91	9	1.52
Completion %	52.66	67.4	1.28
Passer Rating	101.29	158	1.56
First Downs	14.29	20	1.4
3rd Down %	22.04	35.29	1.6
Red Zone %	73.53	50	0.68
Turnover Margin	-0.3	1	x

(Those passing numbers are kind of embarrassing...)

ASU	Average	vs. Cal	Index
Points	26.7	21	0.79
Total YPG	354.6	329	0.93
Rushing YPG	132.8	82	0.62
Rushing YPA	4.48	3.2	0.71
Passing YPG	221.9	247	1.11
Passing YPA	6.1	8.2	1.34
Completion %	53.6	0.57	0.01
Passer Rating	112.31	134.49	1.2
First Downs	18.9	15	0.79
3rd Down %	29	0.33	0.01
Red Zone %	86.21	0.75	0.01
Turnover Margin	1.14	-1	x

 

Finally, here are the index "averages" - note that these are averaged across games, not across plays (i.e. so the average YPA would be the average of each game's YPA, not the average of all attempts over the season).

 

OVERALL	Index
Points	1
Total YPG	1.2
Rushing YPG	0.92
Rushing YPA	0.92
Passing YPG	1.41
Passing YPA	1.19
Completion %	0.95
Passer Rating	1.18
First Downs	1.1
3rd Down %	0.99
Red Zone %	0.93
Turnover Margin	x

 

Again, this is a pretty unscientific way of looking at the numbers - but I think it provides some context to the discussion.

Thoughts? Criticisms? Suggestions? Honkings?