(Bumped. I wondered how teams similar to MSU's effective height perform defensively, read below for more info. Although I wonder how much better State would be defensively on the inside with JaJuan Johnson defending the post - Pete)
In an earlier fanpost I surmised that MSU might struggle on defense due to a lack of effective height on the interior. Well, Ken Pomeroy has posted effective height statistics for the entire division 1 basketball universe on his web site, and now that the statistic is available I thought it would be interesting to look at how MSU stacks up against the rest of the league in terms of both effective height and defensive efficiency.
Ken Pomeroy's effective height statistic is based on the hypothesis that height is important, especially on defense, and that height at the power forward and center positions is more important than height elsewhere. Basically, he surmises that you can get away with a lack of height at the guard positions and still be OK, but a lack of height at center and power forward will, more often than not, result in problems at the defensive end. Ken Pomeroy's article on effective height is here for anyone interested. His analysis looked at the 2008 pre-conference season and found a correlation of .42 between effective height and defensive efficiency. Clearly defensive efficiency does not tell the whole story defensively, but on average it is a significant part of the equation.
MSU is somewhat undersized compared to the rest of the league. Only two teams in the league - Michigan and Iowa - rank below us in effective height. Interestingly, we are tied with Purdue at +0.1. The league leaders are Illinois, with +5.6, Northwestern at +3.8, and Minnesota at +3.2.
As for defensive efficiency, we rank a mediocre 5th in the league. The top 3 teams by far are Minnesota, Purdue and Wisconsin. Ohio State is 4th, but with a significant gap of 5 points per 100 possessions between them and the top three aforementioned defenses. We are basically in a two team second tier defensively with OSU. After us, there is a three point per 100 possessions increase to Illinois, and Northwestern, Michigan, and Penn State are all within roughly a point of Illinois. Iowa's defense is particularly ugly, and they are (perhaps not coincidentally) the most vertically challenged team in the league.
Wisconsin and OSU are, like us, not particularly vertically gifted - both teams have an effective heights of +0.7, ranking them one step above us on the effective height statistic, but still in the bottom half of the league. Given that 4 of the top 5 defensive teams in the league are low on the effective height meter, I decided to run a correlation to confirm my eyeball perception that in the Big 10 this year defense and height are not strongly related. The correlation between adjusted defensive efficiency and effective height for Big Ten teams turned out to be -0.17. Obviously, this is a much weaker correlation than found by Ken Pomeroy for division 1 as a whole. The relationship is of the expected sign - taller teams should allow fewer points per possession, on average, and that is what the data shows.
The good news is that teams with roughly our height profile (Wisconsin and Purdue) are excelling on defense this year. Given this, we should not let our lack of size be an excuse for less-than-excellent defense. Unfortunately, so far we have not demonstrated their ability to overcome our lack of size and be a great defensive team.