defense travels

Background: During the Notre Dame game this past Saturday, the announcers were discussing UVA’s sterling road record and the amount of success they’ve had away from the JPJA, particularly in ACC play.  By way of explanation, Doris Burke said simply, “Defense travels.”  I liked it instantly (not least because that’s all she said, and didn’t spend three possessions blathering on trying to explain it.)

The phrase had a certain elegance, because it made perfect sense.  Hostile crowds are always yelling at you on offense, but they shush when you’re on defense.  You don’t have to worry about shooting backgrounds, giant swirly cutouts during free throws, false countdowns, airball chants, and all the other stuff the crowd throws at you when you have the ball.  In general, offense demands execution while defense demands effort.  (Yes, I know Tony Bennett’s intricate help systems will crash and burn if you don’t execute.  But still.)  It’s not hard to exert effort – it is hard to be mentally sharp enough to execute.

Simply making sense wasn’t quite enough, though.  I wanted to see if I could quantify the concept.  I took, out of the KenPom rankings, the top 25 teams most skewed toward offense and defense, just by dividing a team’s offensive efficiency ranking (out of 351) by its defensive efficiency ranking.  The 25 teams at either end of that list are the least balanced ones.

(This method skews rather heavily toward teams at the top of either list.  I thought of taking every team with a difference of, say, 35 spots between offense and defense, but there’s a huge difference between being ranked #2 and #37, and being ranked #162 and #197.  One is being really good at one thing and decent at another; one is just mediocre at everything.  Clearly, it’s not actually a bad idea to cherry-pick the teams at the top, since the edges of the bell curve is where we want to do this research.)

If defense travels while offense gets stuck at home, you would expect the defense-heavy teams to be about as good on the road as at home, maybe only adjusted by the standard 3-point advantage for home teams.  Similarly, you’d figure offense-heavy teams to struggle on the road.

I decided to look only at conference games, for two reasons.  One, the vast majority of the 50 teams in the study have played an equal number of home and road games inside the conference, while including OOC games would throw that out of whack.  Two, it levels off the quality of competition.  Teams in the ACC, Big Ten, etc., would play a bunch of crappy teams at home and skew the results.  This way teams are playing competition mostly equal to themselves.

The methodology was simply to average each team’s margin of victory or loss on the road and at home and then average all those together.  The result is below.  (Offense-heavy teams are on the left, defense-heavy teams on the right.)

As an example in case the numbers aren’t meaning anything to you, William & Mary has lost by an average of five points on the road and won by an average of 7.14 points at home, the difference being 12.14.  The average team in the offense column wins by 1.64 points on the road and 8.3 points at home.

The obvious, and rather disappointing, conclusion is that the hypothesis is bunk.  The defensive teams actually perform ever so slightly better at home vs. on the road than the offensive teams do – the margin, however, being so close as to be functionally the same.  The correlation between road vs. home performance and defense vs. offense is essentially zero – positively no relationship whatsoever.

About all I managed to affirm with this is that defensive teams generally play somewhat closer games than do offensive teams – like, duh, they do – and that the three-point home-court advantage that linemakers give is fairly spot-on.

But the evidence is plain: it doesn’t matter whether your team is defensively-oriented or offensively-oriented, you’re still subject to the difficulties of playing on the road.  I was really hoping to see a correlation for a couple different reasons.  One of which is that we have a defensive team.  As it turns out, we’re just special.  Only three other teams out of the 50 I looked at have an average double-digit margin of victory on the road, and all three of the others – Davidson, Harvard, and Southern – are mid-majors running roughshod over crappy conferences.  It just turns out that UVA is good on the road not because they’re a defensive team, but because they’re good on the road.