An Investigative Report: Just How Important Were Western Illinois’ Rebounding Abilities Last Season?

Last year’s version of the Western Illinois Leathernecks had a luxury very few Summit teams historically do – two 6’10 bigs who each brought different skill sets that allowed them to effectively share the floor. It provided a size advantage that proved to be huge to the Leathernecks’ success. Just how huge? Let’s find out.

Per KenPom, the Summit League ranked 4^th smallest in average effective height (height weighted for minutes played) out of the 32 Division I conferences, including having 6 of the nation’s 76 smallest teams. Factoring out Western Illinois’ height from the Summit’s average to give a better understanding of their conference foes, the Summit would drop to the 2^nd smallest conference in the nation.

Unsurprisingly to those who watched, this helped Western Illinois lead the Summit League in both offensive and defensive rebound rates during conference play – grabbing 28% of their own missed shots and minimizing opponents to grabbing only 20.4% of their missed shots. The Summit League’s average offensive rebound rate was 24.6% last season.

Now yes, I know purely relegating Western Illinois to an average rebounding team would be a slightly unfair hypothetical experiment because other factors outside of rebounding would, and should, be expected to improve (for example, teams who grab fewer offensive rebounds typically allow less easy baskets in transition thus causing defensive efficiency metrics to improve), but I’m going to perform the experiment anyways and acknowledge there are small factors that simply can’t be projected or accounted for in this investigation.

Let’s set up the data (via KenPom’s conference-only stats):

Now let’s calculate the estimated impact of the hypothetical league-average-rebounding Western Illinois team:

Offensively, their rebound rate would drop from 28.0 to 24.6, a difference of 3.4 percent, or 0.034. Multiply that by their possessions per game (tempo) of 72 and we get 2.448 fewer scoring opportunities per game. Multiply that by their offensive efficiency of 1.051 and the Leathernecks would score approximately 2.57 fewer points per game.

Defensively, their rebound rate would drop from 79.6 to 75.4, a difference of 4.2 percent, or 0.042. Multiply that by their possessions per game (tempo) of 72 and we get 3.024 more scoring opportunities for their opponent per game. Multiply that by their defensive efficiency of 1.086 and the Leathernecks would give up approximately 3.28 more points per game.

Add the two sides up and we get a grand total of 5.85 points per game in their opposition’s favor in our hypothetical world where Western Illinois is a league-average rebounding team.

*Let’s note, these are predictive long-term metrics that will never be perfectly true on a game-by-game basis, but for the experiment’s sake let’s assume they were.

Western Illinois finished with a conference record of 7-11 last season. This included two overtime victories against Denver and NDSU, as well as three other victories that had a margin of 5 points or less. That means if we take into account the estimated 5.85 points-per-game rebounding advantage last season’s Leathernecks had and adjust them to the league average, they would’ve finished with a 2-16 conference record, last in the conference.

Now the questions loom. How does Western Illinois replace the rebounding impact guys like Luka Barisic, Tamell Pearson, George Dixon, and Cam Burrell had? Who are all these new additions and what can they bring to the table? Check back tomorrow for my two-part breakdown of the seven Western Illinois newcomers I see playing an important role for this year’s team.