Monday, December 15, 2008

Maybe Its Both

Apparently I’m not the only one trying to decipher the SEC Defense/Big 12 Offense riddle, as mentioned in my most recent post (“Are Big 12 offenses are strong because Big 12 defenses are weak, or correspondingly SEC defenses are strong because SEC offenses are weak”). Via “Get the Picture” we find another tormented soul trying to solve what Blutarsky calls “one of the toughest issues of the day”- Ed Gunther of “The National Championship Issue”.
Ed seems to believe –as do I – that there is no way statistically to definitively tell if the given result of any game is a cause-and-effect of good offense/poor defense, or vice-versa. However we can look at what we have as evidence, with caution.

The issue I’m looking to address is a little narrower than Gunther’s – whether SEC defenses are superior to their college football peers, or if Big 12 offenses are similarly superior.

Let’s assume that, for our purposes, the games within the conferences are hopelessly tainted by the assumptions that –

A. Big 12 defenses are so bad that their offenses look better than they are in reality, and;

B. SEC offenses are so bad that their defenses look better than they are in reality.

Our “hypothesizes”, if you will.

In order to remove the taints of both "flawed" conferences, we will look at their games against non-conference opponents only. Obviously this is imperfect as sampling as there were very few games between common teams (Wake Forest, West Virginia and Rice managed to both play SEC and Big 12 teams), and the sample size is limited. Further the quality of teams played is open for debate. That said, it is what we have.

First the Big 12. The following chart shows every FBS non-conference Big 12 opponent with the score of each team following the team. The last two columns show the opponents average points for the year scored on offense, and surrendered on defense.
For example in looking at the Baylor game against Wake Forest at the top, Baylor scored 13 while Wake scored 41. Wake holding Baylor to 13 was 5.3 pts better than their season average of 18.3, while scoring 41 was 20.7 pts better than their season offensive average.

By totaling the columns and comparing them we can see how much better the Big 12 did on offense and defense against non-conference opponents than those team’s season averages. The totaling get us thus –

Big 12

Total Scored against non-conference opponents – 1435
Total Surrendered to non-conference opponents – 815

Total of average PPG defense of non-conference opponents – 1055
Total of average PPG offense of non-conference opponents – 994

What this tells us is that we could have “expected” the non-conference opponents, based on their averages, to surrender 1055 points to the Big 12 when in fact they gave up much more in 1435. Likewise we could have “expected” them to score 994 when, in fact, Big 12 defenses held them to 815.

As a percentage for comparison purposes –

Offensive Prowess: 136% (1435/1055 = 1.3602)
Defensive Prowess: 82% (815/994 = 0.8199)

So Big 12 offenses scored 136% of what one would expect based on their opponent’s season averages, and the defenses held their opponents to 82% of what the average would dictate.

Now for the SEC


SEC

Total Scored against non-conference opponents – 1072
Total Surrendered against non-conference opponents – 624

Total of average PPG defense of non-conference opponents – 938
Total of average PPG offense of non-conference opponents – 960

Once again this tells us is that we could have “expected” the non-conference opponents, based on their averages, to surrender 938 points to the SEC when in fact they gave up more in 1072. Likewise we could have “expected” them to score 960 when they were held by the SEC to 624.

As a percentage for comparison purposes –

Offensive Prowess Percentage: 114.3% (1072/938 = 1.1429)
Defensive Prowess Percentage: 65% (624/960 = 0.65)

Based on this SEC offenses scored 114% of the points one would expect based on their opponents season averages, and surrendered only 65% of what one would have anticipated on defense.

Head-to-head

Big 12 against non-conference opponents

Offensive Prowess: 136% (1435/1055 = 1.3602)
Defensive Prowess: 82% (815/994 = 0.8199)

SEC against non-conference opponents

Offensive Prowess Percentage: 114.3% (1072/938 = 1.1429)
Defensive Prowess Percentage: 65% (624/960 = 0.65)

Now I’m not surprised in the least that, given the general quality of the non-conference opponents faced, that in both cases the offenses scored more than expected, and the defenses held their opponents to less. I’d be shocked if it were otherwise.

And, although it is subject again to sample size and member limitations, the Big 12 seems to have a more effective offense, while the SEC has a more effective defense even when their conference opponents are taken out of the equation.

In other words, in answer to our original question – the answer may be “both”.

5 comments:

Jams said...

That last set of numbers is interesting, because it shows that the SEC defenses are about as good (speaking in percentages) as the Big 12 offenses, and vice versa.

Amos said...

I think it would be interesting to see how this stacks up against the rest of the conferences (at least the bcs ones). That way we can see if this metric supports common assumptions about the different conferences. Is the Big 12's offensive prowess actually the highest among conferences, is the SEC's defensive prowess actually the best as well?

Trader Rick said...

What it boils down to is this:

1. We haven't faced an offense quite as good as theirs; They have faced offenses as good as ours.

2. We've faced defenses better than theirs; They haven't faced a defense anywhere near as good as ours.

Slight edge to Gators.

AceG8tr said...

And sorry for the overused maxim, but:

"defense wins championships."

See 2006.

Datadatum said...

So just for fun, why not place the big 12 offense against the SEC defense...

Big 12 scores... 136% * 65% = 88.4%

And the SEC offense against the Big 12 defense...

SEC scores... 114% * 82% = 93.7%

So the SEC Wins!

Well, er... or something like that. ;)