First, let's look at the Badgers:
Wisconsin allowed an average of 22.6 points per game. The offenses they faced typically scored 26.4 points per game. That gives the Badgers defense a net gain of 3.8 points per game. That means they allowed nearly 4 points fewer per game than a typical opponent given the teams they played.
Their best defensive games were against Indiana (-29), Northern Illinois (-16), and Iowa (-6). They allowed fewer than expected point totals in 7 games and over expected totals in 4 games. Their worst games of the year were Penn State (+8), Minnesota (+8), and Ohio State (+6). Of note is that they started the year with 4 pretty solid defensive performances, but were only 3 out of 7 in their last 11 games. However, it also should be noted that other than the IU and NIU games, they were always within about a touchdown either way of being average.
Now, how about the Volunteers:
Tennessee allowed an average of 26.6 points per game. The offenses they faced typically scored 30.1 points per game. That gives the Vols defense a net gain of 3.5 points per game.
Their best defensive games were against LSU (-18), Arkansas (-27), and Georgia (-18). They allowed fewer than expected point totals in 8 games and over expected totals in 5 games. Their worst games of the year were Cal (+17), Florida (+16), and Alabama (+14). What is interesting about Tennessee's defensive performance is that unlike Wisconsin, which was pretty consistently average, the Vols defense was either really really good or pretty bad. There weren't nearly as many "average" games as you saw with the Badgers. It also bears noting that 3 of Tennessee's poor games came in their first four games.
Unlike scoring offense, where the teams faced very comparable defenses, the Volunteers faced much tougher offenses, which accounts for the difference in their points allowed numbers. Wisconsin does get a very very slight edge statistically, though 0.3 points per game really doesn't have any real significance. While, I think Wisconsin's defensive performance looks pretty easy to predict, who really knows what you are going to get from Tennessee. This could wind up as a big edge for either team depending on which Vol team shows up.
So, what do we know so far? Both teams have better offenses than defenses. The Tennessee offense appears to be better than the Wisconsin offense, while the Wisconsin defense and Tennessee defense are basically even. If we were to rank the units, it would look like this:
1. Tennessee offense +7.3
2. Wisconsin offense +4.8
3. Wisconsin defense –3.8
4. Tennessee defense –3.5
The net comparison gives Wisconsin an 8.6 point edge over their opponents, while Tennessee gets a 10.8 point edge, while attempting to control for the opposition.
Next: Wisconsin rushing offense vs. Tennessee rushing defense