The NumbersU. Dayton BasketballThe Numbers Behind Dayton’s Offensive Rebound Woes

Matt breaks down UD's offensive rebounding shortcomings
Matt Rhein4 months ago29 min

At the beginning of the season, few Dayton fans would have dreamt that the Flyers would sit ranked 6th in the AP Poll. Even the most optimistic among us surely couldn’t have predicted this. Despite that, there are a few areas of concern that most fans have for the squad. The most common area fans of the Flyers would like to see cleaned up comes in conceding offensive rebounds.

As Dayton’s success this season brings loftier expectations this season from the fan base, it is only natural to fret over any shortcomings. The anecdotal evidence certainly seems to point to a deficiency in offensive rebounding. Recent games against Saint Louis and Duquesne have helped to highlight this, but do the numbers suggest the Flyers are bad rebounders?

There are a few ways to determine this. First, we can look at the traditional offensive rebound rate. We calculate this by dividing the number of offensive rebounds UD gives up by the opponent’s offensive rebounds and UD’s defensive rebounds.  So far this season, Dayton has conceded a 26.8% offensive rebound rate to opponents. This is below the nationwide average of 28.2% and ranks the Flyers 113th among D1 teams. If we parse this out to only Atlantic 10 opponents, it drops to 24.84%. So UD isn’t the worst in allowing second chances for opponents, but they certainly aren’t the best.

However, as many pointed out at the beginning of the season and Sully went into very specific detail about one specific example, there are a lot of bad teams in both UD’s non-conference schedule and in the A10. Yet even against opponents in the Top 100 in the KenPom ratings (Indiana St., Georgia, Virginia Tech, Kansas, St. Mary’s, North Texas, Colorado, VCU, St. Louis, Richmond, and Duquesne as of writing so far) Dayton’s opponents offensive rebound rate is at 26.69%. Not great certainly, but still not terrible. Is there more to the story though?

The opposing team getting an offensive rebound is one thing but allowing second chance points against teams that likely don’t have the offensive firepower the Flyers do is another. Giving teams multiple chances to score is exactly what can lead to an upset against Dayton, so are teams converting these second chances against UD? Using the r package ncaahoopR, we can scrape play by play data and try to answer that question.

This season, Dayton’s opponents have scored 0.938 points per possession on offensive rebounds. Against Atlantic 10 opponents so far, it is a similar 0.937 points per possession. These aren’t averages that will really kill a team, so is the offensive rebounding problem for the Flyers overblown? Unfortunately if we turn our attention to Top 100 KenPom teams Dayton has matched up with, we see where the issues start to appear. Those teams have averaged 1.143 points per possession, which certainly starts to ring the alarm bells.

It seems obvious, but elite teams are better at making you pay from offensive rebounds. While the Flyers still have a few more tomato can A10 opponents left, they also still have games against SLU, Rhode Island, VCU, and Duquesne remaining. Furthermore, as we get closer to March, the Flyers will hopefully have many more games against top opposition. Giving these good teams multiple chances at scoring against Dayton could be the difference between a long run in March Madness and going home early.

So the numbers confirm good teams have been hurting Dayton on second chance opportunities. Can we learn anything else about the scenarios that the Flyers give up these rebounds? With the same data I’ve scraped using ncaahoopR, we sure can! Inspired by this post on Nylon Calculus discussing rebounds, we can see what types of shots are most likely to see Flyer foes get the rebound. The lucky so-and-so’s at Nylon Calculus have tracking data, so they can take it a step further and find where a rebound is most likely to go based off of the type of shot. We will just have to be content with the types of shots leading to UD giving up an offensive rebound.

The types of shots Dayton is allowing offensive rebounds on.

Over 65% of the offensive rebounds that Dayton has given up this season have come from jump shots. It is nearly identical the number of second chance opportunities the Flyers has conceded from threes and mid-range jumpers at 33 and 32% respectively. Layups, blocks by UD, and free throws make up a much smaller chunk of the offensive rebounds Dayton’s opponents have gotten. This makes sense logically as we think back to the old saying of “long shots create long rebounds”. What the Flyers can do about this now becomes the question?

In the previously referenced article on Nylon Calculus discussing rebounding, they were able to find the locations where rebounds most went to based on where the shot occurred.  They found that 41% of attempted threes are rebounded 7 to 21 feet from the basket, while 40% of mid-range shots are rebounded 4 to 6 feet from the basket. These are the highest chunks of where these rebounds were gathered for each of these types of shots. Of course the skill level in the NBA where this data comes from is higher than college basketball, but for shots that are missed, I don’t think it is outlandish to think similar trends exist in the college game.

So what can the Flyers do? Besides curse and yell to box out (which I have done plenty of this season), UD can use these numbers to try and position themselves better and mitigate offensive rebounding opportunities for opponents. Since we know that most of the rebounds UD give up come from shots from deep and the mid-range, the Flyers can play the percentages and try to position themselves near the free throw line for threes and 4-6 feet on mid-range jumpers. There obviously is more to rebounding than being in the right place, but good positioning can be the first step to restricting second chances for the other team.

Admittedly, it is a bit refreshing to try and dissect smaller scale problems like this instead of some larger flaw for the Flyers. The talent on this Dayton team is so unprecedented that instead of having to discuss macro issues, UD fans are instead concerned about an issue that only happens in a quarter of the possessions in a typical game. Nevertheless, as the Flyers are mentioned as possible national championship contenders, these small issues are what need to be addressed if Dayton is to take that giant step up.

Matt Rhein

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