Is an Elite ORB% Sustainable?

   Welcome back! In writing a previous article about the top ORB% leaders in the country for the 2019-2020 season, I found that I was very optimistic that the guys on the list would be able to sustain at least similarly high offensive rebounding rates heading into next season. This was especially true for players averaging 20 mpg or less, as I was excited to see what they could do with additional minutes. However, I began to wonder if such optimism was warranted. With more minutes in the next season, we would expect ORB% to decrease slightly. This is because ORB% measures the percentage of available offensive rebounds that a player grabs while he's on the court. Thus, more minutes played means more offensive rebounds a player needs to get in order to maintain the same rate. I was hoping to determine just how big this ORB% drop off is, and if it's small enough for players to still have an elite ORB%. Also, I wanted to see if the drop off was worth the increase in minutes.

    To find out, I looked at the top 50 players in terms of ORB% from the past 4 seasons on Sports Reference. I removed players whose top 50 ORB% season was his last in college and any players who transferred. I then calculated the minutes per game increase or decrease following the elite ORB% season and how much the player's ORB% changed after the top 50 season. For instance, Michigan State's Nick Ward had a top 50 ORB% season in 2017-2018, so I compared his minutes per game and ORB% to the following 2018-2019 season. Here's the results:

    As you can see, the vast majority of players experienced the expected decline in ORB% as their minutes increased. To answer the first question posed in the introduction, most players saw a decline of about 1-6%. While it's a decent decrease, to be in the top 50 in terms of ORB%, these players had an ORB% of somewhere between 13-18% in their standout season. Even a drop of 6% in the next season would mean at worst an ORB% of 7%. This is hardly elite anymore, but isn't completely awful.

    Somewhat surprisingly, ORB% also decreased in players who experienced significant minute reductions. You'd think that a player's ORB% would go up with fewer minutes because they'd have to be locked in on getting offensive rebounds for less time per game to maintain the same ORB%. Perhaps ORB% mostly declines along with minutes due to underlying poor play. For instance, coaches may have been unimpressed during the offseason/beginning few games and decided to cut these players' minutes. In this scenario, the players may have simply been not as good as they were in the prior season which could yield fewer offensive boards and a lower ORB%. 

    While ORB% seems to decline after an elite season for most players, there are a few who buck this trend and preserve or improve their already high ORB% in the following season. Most of such players experienced minimal changes in the amount of minutes that they played. This might suggest that these players were already operating in a role that maximized their offensive rebounding efficiency. By either pure luck or intentional strategy, their coaches opted to keep these players' minutes the same and benefited from another excellent ORB% season. Unfortunately, there are also plenty of players who undermined this pattern as they played roughly the same minutes the following season and saw their ORB% drop, sometimes significantly. Thus, getting a player to maintain an exceptional ORB% isn't as simple as holding his minutes the same.

    Given that we largely see a decline in ORB% in most players who saw more minutes in the next season, it's important to take a look at what's driving this drop. Is it that players are getting fewer offensive rebounds overall in the following season, or is the minute increase greater than a player's offensive rebounding increase? To achieve this, we can color each point of the above graph according to how many more (or fewer) offensive rebounds per game a player got in the next season. Green indicates a large increase and red indicates a large decrease. Here's what the new, color-coded graph looks like:

    As would be expected, pretty much every player who experienced a minutes reduction also grabbed fewer offensive rebounds in the following season. It certainly makes sense as less time on the court means less opportunities to get rebounds. Also, the few standouts who were able to meet or exceed their previously impressive ORB% were actually able to get more offensive rebounds per game as well. These players were especially useful as they maintained their offensive rebounding efficiency while also increasing their volume of offensive rebounds. Most interestingly, we see from the graph that the majority of players who saw increased minutes also increased their rebounds per game. This means that their decrease in ORB% was caused by their minute increase outpacing their offensive rebounding increase. This is important because it suggests that the decrease in ORB% may not be such a bad thing after all. When these players were given expanded minutes, their offensive rebounding didn't suddenly get much worse, it just didn't improve at quite as rapid of a rate.

    It's also important to consider what else these players are doing in their increased minutes. After all, most coaches won't give a guy 5-10 extra minutes per game expecting him to only focus on increasing his offensive rebounding. An area that I thought would be especially important to look at is scoring. If a player is going to play significantly more per game, they'll likely need to chip in with more points. The following graph is the same as the previous two, but is colored by the points per game increase or decrease in the following season. Like the last graph, green indicates the largest scoring increase and red represents the largest drop.

   Mirroring the trend in the previous graph of players who had a minutes reduction getting fewer offensive rebounds per game, these players also scored less. Even players who kept roughly the same minutes and maintained or improved their ORB% varied in terms of if they were able to increase their scoring or not. While these players kept a high rebounding efficiency and increased their rebounding volume, scoring didn't always follow suit. Meanwhile, most players who experienced an increase in minutes also experienced a scoring boost, even if it was just a slight one. Thus, this benefit to the team serves to somewhat counteract the ORB% decline.

    After diving into these three graphs, it's time to return to the second question posed in the introduction regarding if the minutes increase is worth it. The answer to this is that it really depends. The second and third graphs revealed that a decrease in ORB% isn't inherently a bad thing because players can still increase their offensive rebounding volume at the expense of some efficiency while also improving other skills such as scoring. However, the tricky part is determining whether the incremental offensive rebounding and/or scoring increase is worth sacrificing an excellent ORB%. I think it's safe to say that players such as those represented by the two green points furthest to the right on the above graph are cases where it's worth it. An increase of 5-10 points per game is likely more valuable to their respective teams than about 5% of lost ORB% considering that their rebounds per game also increased. It gets more difficult when comparing say a 1 point per game scoring increase to a 3% drop in ORB%. 

    Ignoring team-specific roster situations, it seems as though in general coaches may as well risk worse offensive rebounding efficiency with increased minutes in the hopes of more overall production from their players. Chasing the same elite ORB% efficiency as the previous season by keeping minutes the same appears to be just as risky. Overall, my optimism in the previous article was a little excessive because we've seen that an elite ORB% is only sustainable in rare instances. However, this sustainability doesn't seem to be desirable to aim for in the first place. 

    Thanks so much for reading if you've made it this far! Be sure to check out some of my other articles if you enjoyed this!

Offensive Rebounding Leaders vs. Defensive Rebounding Leaders

    Welcome back! If you missed my previous article comparing offensive rebounding percentage (the percentage of available offensive rebounds a player got while he was in the game) to offensive ratings (the number of points that a player produces for every 100 possessions) for the top 20 players in terms of ORB%, you can find it here. If you missed the similar article comparing defensive rebounding percentage (the opposite of ORB%) to defensive ratings (the number of points that a player allows for every 100 possessions), you can read that one here. This article combines the data from those two articles, so it might be helpful to skim them at least for reference.

    The goal of this article is to compare ORB% to DRB%. This will help us to figure out which players are specialists on the offensive glass only, defensive glass only, and who are all-around dominant rebounders. We'll look at both the ORB% and DRB% for the top 20 players in terms of ORB% and the top 20 players in terms of DRB%. Essentially, we're combining the two sets of players from the previous two articles. Both the ORB% and DRB% data comes from Fox Sports. Any additional data comes from Fox Sports or Sports Reference.

Here's what the graph looks like comparing ORB% and DRB%:

As always, here's the complete list of players for reference:

Oscar Tshiebwe - West Virginia

Jordan Minor - Merrimack

Ed Croswell - LaSalle (now Providence)

Kevin Marfo - Quinnipiac (now Texas A&M)

Trevion Williams - Purdue

Austin Wiley - Auburn

Scottie James - Liberty

Tyrique Jones - Xavier

Cletrell Pope - Bethune-Cookman

Patrick Harding - Bryant

Chris Harris - Houston

Freddie Gillespie - Baylor

Myles Johnson - Rutgers

Loudon Love - Wright State

Austin Phyfe - Northern Iowa

Mubarak Muhammed - Louisiana Tech

Omer Yurtseven - Georgetown

Mahamadou Diawara - Stetson

Udoka Azubuike - Kansas

Josh Mballa - Buffalo

Brison Gresham - Houston

Nate Watson - Providence

RJ Williams - Boise State

Dave Bell - Jacksonville

Emanuel Littles - North Alabama

Nico Carvacho - Colorado State

James Dickey - UNC Greensboro

Aaron Carver - Old Dominion

Dwight Wilson - James Madison

James Butler - Drexel

John Mooney - Notre Dame

Nathan Knight - William & Mary

Joel Soriano - Fordham

Kai Edwards - Northern Colorado

Ahsan Asadullah - Lipscomb

Yoeli Childs - BYU

Elyjah Goss - IUPUI

Tyler Bey - Colorado

Carlos Dotson - Western Carolina

Lowest ORB%, Highest DRB%

    Since we're looking at some of the most elite rebounders in the country, no players are found in the bottom left corner as they're at least specialists in one of ORB% or DRB%, if not both. We can just skip that empty area and move up to the top left corner which is where defensive rebounding specialists are found. The two players we'll focus on from here are Tyler Bey and Yoeli Childs.

Tyler Bey - Colorado

    We've actually already looked at Bey in the article about defensive rebounding percentage vs. defensive rating. We saw that on top of being a great defensive rebounder, he was very good in other defensive attributes such as blocks (1.2 per game), steals (1.5 per game), and limiting fouls (1.9 per game). It makes sense why he has a lot of NBA draft intrigue due to his defense. According to the chart, his offensive rebounding percentage could be seen as a weakness as it's just over 9%. However, Colorado was only a slightly above average team in terms of ORB%, so offensive rebounding likely wasn't a huge priority for Bey. This is especially true given his 55.5% EFG% as his value as a shooter made it more costly to give up a potential open look from a kickout to try to get the rebound himself. 

Yoeli Childs - BYU

    Childs only managed to suit up for 19 games this past season, a byproduct of a 9-game suspension for an NCAA paperwork issue coupled with a dislocated finger. However, he was a tremendous asset to the Cougars when he did play, and was a big part in the team being seen as comfortably in the NCAA Tournament field and as having the potential to make a run. Since he missed so many games, Childs still ended up with an 8.8% ORB% despite having only gotten 38 total offensive rebounds during the season. This is well behind even Bey's low total of 62. Nevertheless, he still had the best ORB% on his team. Ultimately, this didn't matter too much because BYU shot the ball so ridiculously well that offensive rebounds weren't as critical for the team. Thus, they actually ended up 343rd in the nation in total offensive rebounds. While not super active on the offensive glass, Childs was relied upon to get defensive rebounds partially because of the lack of height on this BYU squad. The Cougars were actually quite a good defensive rebounding team aside from Childs, but him being the second tallest of players who played significant minutes at 6'8" provided a helpful boost.

Highest ORB%, Highest DRB%

    As we head over to the top right corner of the graph, we see some of the best out of this already elite group of rebounders. They truly excelled on both the offensive and defensive glass and dominated with their positioning and physicality. We'll focus on three players who are most clearly in this corner: Kevin Marfo and Patrick Harding (as promised in my last article) as well as Austin Wiley.

Kevin Marfo - Quinnipiac (now Texas A&M)

    Marfo topped the list of highest DRB% at 36.9% and wasn't too far off the top in terms of ORB% with his 19.9%. Given his dominance in both of these metrics, it's no surprise that he entered the abrupt beginning of the offseason as a highly-sought grad transfer. He ultimately decided to take his talent to College Station to play for Coach Buzz Williams and the Aggies. The big question is, will he be able to maintain such high rebounding percentages? The reason for optimism is that Marfo's incredible rebounding numbers didn't occur because he dominated in limited minutes. Rather, he was a 28.1 MPG game guy and grabbed 134 total offensive rebounds and 265 total defensive rebounds. It has to be mentioned that while he got both a large percentage and volume of rebounds when he was in the game, he was doing so in the MAAC. There's a clear step up in size and physicality of bigs going to the SEC that Marfo will now have to battle against to repeat such an incredible season. The only Power 5 competition that Marfo faced this past season was ACC foe Miami, and he had no trouble in getting 3 offensive boards and 10 rebounds on the defensive end. Unfortunately, Miami was a pretty bad rebounding team and so this doesn't really give us great insight as to whether Marfo can truly hold his own against higher level opposition. Overall, there's definitely evidence to support Marfo fitting right in and helping the Aggies improve upon their 30.9 rebounds per game this past season, but we'll have to wait until the first few games to truly know.

Patrick Harding - Bryant

    Harding achieved his awesome DRB% and ORB% through only 18.8 MPG, so almost 10 MPG less than Marfo. This past season, his sophomore year, Harding had a bit of a breakthrough in terms of rebounding. While his minutes only experienced a slight uptick (17.5 to 18.8 per game), he almost doubled his total rebounds and had 94 total offensive rebounds and 186 total defensive rebounds. Accordingly, his DRB% and ORB% rose to get him towards the top of both of these lists nationally. Judging from these percentages only, it seems as though Harding's performance on the boards has warranted a more dramatic minute increase than the one that he had this past season. One concern is that he only scored 4.7 points per game, but he did so with a very good 61.3% EFG%. Therefore, he should be able to fill more of a scoring role with his efficiency. Coach Jared Grasso's group is projected to improve upon their 7-11 conference performance from this past season, and I can see Harding playing a strong part in that.

Austin Wiley - Auburn

    Wiley had a pretty solid freshman season for the Tigers, but his college career took a strange turn when he was forced to sit out of the 2017-18 season due to a potential recruiting violation related to assistant Chuck Person. He couldn't have asked for a better season to return to as 2018-19 was when Auburn made its legendary Final Four run. He didn't have huge role on that team being only a 6.9 ppg and 4.0 rpg guy, but he was doing so on 13 minutes per night. This past season, he was given a larger role with 21.4 minutes per game and has certainly delivered. He got his scoring up to 10 ppg with an effective 57.4% EFG%. His biggest strength though, of course, was rebounding. His DRB% and ORB% both increased significantly and he's now one of the best rebounders in the nation according to this metric. Wiley certainly has bounced back from the challenges of 2017-18 to become an elite rebounder and member of a Final Four squad.

Highest ORB%, Lowest DRB%

    We finish off the analysis in the bottom right corner to look at offensive rebounding specialists. Like the defensive rebounding specialists above, just because these guys specialize more in one rebounding area, it doesn't mean that they're a liability on the glass on the other end. We'll look at both Chris Harris and Jordan Minor.

Chris Harris - Houston

    I mentioned Harris in my previous article about ORB% vs. offensive ratings when talking about another Houston player that can be found on the above graph, Brison Gresham. I mentioned how Harris has graduated and how his loss will be tough for the Cougars to replace because of his rebounding ability. Rebounding was a huge priority for last season's Cougars as they were part of a three-way tie for the most rebounds per game with 38.6. They also had the second best ORB% at 39%. Harris was a strong part of this as he had the best ORB% on the team. He almost doubled his total offensive rebounds from 42 in the 2018-19 season to 80 this past season. This worked out to be 2.7 per game on only 17.9 mpg. As mentioned in my previous article, guard Nate Hinton who's more of a defensive rebounding specialist is also leaving the program to go pro. The Cougars certainly have their work cut out for them if they want to reign atop the NCAA rebounding rankings once more.

Jordan Minor - Merrimack

    Minor was the ultimate newbie this past season having been a freshman on a Merrimack squad in its first season of Division I hoops. While not a huge scoring threat yet with only 6.2 points per game, Minor's 20.5% ORB% was a huge benefit to his team. This is because the Warriors weren't a great offensive rebounding team having only gotten 6.4 per game which contributed to a 20.4% ORB%. Somewhat surprisingly, Minor's individual ORB% was better than his overall team's which hasn't been the case for the aforementioned players. To further emphasize just how key Minor was to Merrimack's offensive rebounding, he himself got 2.6 of the 6.4 team offensive rebounds per game. It'll be interesting to see if Minor can continue to shoulder such a large portion of the offensive rebounding load, especially if he sees more time on the court. I think there's certainly a case to be made for this to happen. He had a 105.8 ORtg as a freshman which is pretty solid, and he showed flashes of scoring potential such as going 6-9 for 15 points against Jacksonville. The key for him will to be to maintain his excellent offensive rebounding ability while improving his game in other areas.

Overall Thoughts:

    I really enjoyed writing this three-part series of articles on DRB% and ORB% because it of course highlighted well-known elite rebounders such as Marfo who play a lot of minutes and thus have a large volume of rebounds. However, it's also nice to see credit given to players who simply make the most out of the more limited minutes that they're given, a player like Patrick Harding or Chris Harris. We saw that a lot of players in the graph are pretty good at both offensive and defensive rebounding which makes sense as the two skills are very similar. Yet there are a few clear specialists in either DRB% or ORB%, and we had to dive deeper to see why that was so. For instance, Childs was more of a defensive rebounding specialist because his team shot so well and offensive rebounds weren't as essential, whereas Chris Harris had many good defensive rebounding teammates like Nate Hinton and so he specialized more on the offensive end. Despite not being as flashy as scoring, rebounding is critical to the game of basketball, and all of these players deserve praise for excelling in this area.

Thanks so much for reading this far, I hope you enjoyed it! Be sure to check out some of my other articles!