In the last edition of "hoops analysis," I explored the deep end of tempo adjusted efficiency. I used data from "Kempon" to put the current Michigan State basketball team's performance to date into perspective.
What we learned is that so far, the Spartans have only played at a level of efficiency that suggests an early exit from the NCAA tournament is most likely. While there is still plenty of time for the team to improve, the numbers so far suggest that Michigan State is far closer to the bubble than they are to the Final Four, which is always a top goal in East Lansing.
Today, I would like to explore some of the reasons why Michigan State's statistics are found to be lacking. The best way to do this is to explore the concept known as "the four factors."
What are the four factors?
The "four factors of basketball success" is a concept that was introduced in the landmark book called Basketball on Paper by Dean Oliver. They are now essentially a universally accepted collection of the four most critical statistics to capture in any basketball game. There are, in order of importance:
- Effective field goal percentage (eFGPct)
- Turnover percentage (TOPct)
- Offensive rebounding percentage (ORPct)
- Free throw rate (FTRate)
These statistics are calculated both on the offensive and defensive end.
Effective field goal percentage is essentially a measure of how many points a team scores (or gives up) per shot attempt. There is a correction factor in the formula to account for three-point shots such that shooting prowess can be captured using a single value. It is not hard to understand why this is the most important of the four factors. The basic object of the game is to make baskets while preventing the other team from making baskets.
The second and third of the four factors are very close to equal in importance. Both factors have to do with maximizing the number of shot attempts. Turnover percentage simply measures the frequency at which a team turns the ball over. A turnover is a lost attempt at taking a shot. On the other hand, offensive rebounding offers a second chance to potentially take a shot. These two factors are essentially opposite sides of the same coin.
The final of the four factors is free throw rate (free throw attempts per field goal attempt). This essentially measures the number of times team gets to the free throw line, which is of course the only way to score that is not measured by effective field goal percentage.
These four factors together can be used to measure a team's raw offensive and defensive efficiency. It is therefore possible to understand any team's overall efficiency by looking at the four factors.
The Four Factors in the Big Ten
How is Michigan State currently performing in each of the four factors? Table 1 below lists both the offensive and defensive numbers for all 14 Big Ten teams as of Dec. 31, 2022. Note that the teams are listed in the order of their current Kenpom ranking. The Spartans are currently ninth in the Big Ten in that metric and No. 42 nationally.
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| Table 1: Summary of the "four factors" on both offense and defense for the Big Ten as of Dec. 26. |
The numbers in paratheses following each value are the current Big Ten and national rank for that metric.
In my previous article, I pointed out that Michigan State appears to need a bigger improvement on the offensive side of the ball and these numbers seem to support that observation. Michigan State's offensive effective field goal percentage is ranked No. 9 in the Big Ten and very average nationally at No. 140.
Why are the Spartans' shooting numbers so mediocre? If we dig a bit deeper into the numbers, we find that Michigan State's three-point shooting is actually pretty good. As a team, the Spartans are currently shooting 38% from deep which is good enough for No. 30 nationally and third in the Big Ten behind only Penn State and Wisconsin.
However, the story is quite a bit different from inside the arc. The Spartans are only making 47.6% of their two-point shots right now, which is ranked No. 253 nationally and No. 12 in the Big Ten ahead of only Northwestern and Wisconsin.
The Spartans are also doing a very poor job on the offensive glass (No. 11 in the Big Ten and No. 207 nationally) and are even worse at getting to the free throw line. MSU ranks No. 297 nationally in that category, which only tops Penn State in the conference.
Ironically, the only offensive four factor where the Spartans are currently in the top half of the conference is turnover rate, which Michigan State is ranked No. 6 in the Big Ten and No. 49 nationally. This has historically been the factor on offense where the Spartans have struggled.
On the defensive side of the ball, Michigan State is dead last in the conference (and No. 342 nationally) in creating turnovers and ranks only No. 10 in the Big Ten (but No. 80 nationally) in avoiding fouls. But the other two factors on defense are a little better.
The Spartans currently rank No. 9 (and No. 60 nationally) in effective field goal defense. Best of all, Michigan State is currently ranked No. 3 in the Big Ten is defensive rebounding behind only Purdue and Wisconsin. Nationally, this rate is good enough for the Spartans to be ranked No. 45.
Comparing Michigan State to other Big Ten teams does provide some perspective. But, most of the games played so far have been against out-of-conference opponents and the strength of each Big Ten team's schedule is highly variable.
In addition, some programs simply value each of the four factors differently. Under Tom Izzo, rebounding is more important than avoiding (or creating) turnovers. In order to put the performance of the 2022-23 Michigan State team into context, it is also helpful to compare this year's team's numbers to those of past Spartan squad.
Comparison to Past Michigan State Teams
In order to better visualize how the Spartans typically grade out on each of the four factors, I have created a box plot shown below in Figure 1.
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Figure 1 contains four sets of data. Most prominent are the eight "boxes with whiskers." These symbols represent the range of performance for all past Michigan State teams back to 1997. Each rectangle represents the range of values posted by half of Tom Izzo's teams. The line separating the two colors in each box is the median value for each statistic.
Each "whisker" (or error bar) represents the top (or bottom) 25 percent of performances for each metric. So in summary, each box and whisker shows the full range of values including each "quartile."
As an example, in this timeframe (1997 to now) Michigan State's median offensive rebounding performance is 36.6 percent. In other words, half of Tom Izzo's teams have posted better numbers than this while the other half of his teams have done worse. The team closest to this median is the 2018 team with an offensive rebounding rate of 37%.
Half of the Michigan State teams since 1997 have grabbed between 33% and 39% of their missed shots. Therefore the green and white rectangle in the third column therefore spans from 33% to 39% with the line between the two colors at 36.6%.
A quarter of the previous Spartan teams have grabbed more than 39% of their missed shots. The best performance on record is the 2001 team which had an offensive rebounding rate of 47%. In contract, a quarter of Tom Izzo's teams have posted an offensive rebounding rate below 33%. Michigan State's worst offensive rebounding team in the last 26 years was the 2017 team, which grabbed only 29.2% of their misses.
In addition to the boxes and whiskers symbols, each column contains three additional data points. The solid diamonds are the overall performance for the 2022-23 Michigan State team in each area. The circles represent the Spartans' two most recent performance, in this case in the games against Oakland and against Buffalo.
One additional note that is annoying about the four factors is that for some of the factors, a larger number is good, while for others, a smaller number is good. In addition, the situation is reserved for offensive values versus defensive values.
In order to clarify which is which, I have color coded the boxes and data points. If a box or diamond is green or white, that means that bigger numbers are good and/or the current performance is above average relative to past Michigan State teams. If the box or symbol is a combination of blue, yellow, or red, that means than smaller numbers are good and/or the current performance is below average.
With this information in hand, let's now review what Figure 1 is telling us. As table 1 above indicated, the 2022-23 Michigan State team, so far, is a below average shooting team. The current shooting numbers, if they are maintained would be in the lowest quartile (i.e. the bottom 25 percent) of Tom Izzo teams.
But, that is not the worst news. Table 1 above highlighted some of Michigan State's problems on the offensive glass and in getting to the free throw line. But Figure 1 shows that both of these factors are currently at historically poor levels. If Michigan State continues to hover at an offensive rebounding rate close to 30%, the 2022-23 team will be the worst offensive rebounding team in the past 26 years.
Even stranger is the free throw rate data. Michigan State's current free throw rate of just 25.9 percent is currently at a historical low point, and it is not even close. The 2016 teams team posted a rate of 30 percent, and that is the lowest value on record for the Spartans.
The good news for the Spartans this year continues to be the turnover performance. Michigan State's current turnover rate of 16.3%, if it holds up during Big Ten play, is the best performance of the Tom Izzo era. Both the 2014 and 2015 teams had rates of 17.4%. For better or worse, the positive turnover performance is helping the mask some of the struggles on the offensive glass.
In Michigan State's most recent performances, the shooting certainly was improved. The Spartans posted an effective field goal percentage of over 57% in both games. The turnover and free throw rate factors both showed improvements over the Christmas holiday. Michigan State had a very poor turnover performance against Oakland and barely shot any free throws at all. Against Buffalo, however, the Spartans once again did an excellent job of avoiding turnovers. In addition, Michigan State's free throw rate of 50.9% was the second best of the year.
Unfortunately, Michigan State continues to do a poor job on the offensive glass. Against Oakland and Buffalo, the Spartans actually had a below average offensive rebounding performance compared to their already poor performance year-to-date. Spartan fans may just need to accept that this factor is not going to get better this year.
On defense, Figure 1 shows that the 2022-23 Michigan State team is relatively strong in two area, and relatively weak in two other areas. While the Spartans have struggled to rebound the ball on offense, their ability to clear the defensive glass (24.7%) is currently at a level that would rank second in the Izzo era behind only the 2009 National runner up team.
The current team in East Lansing is also displaying a historically good tendency to avoid fouls. Michigan State's opponents have a free throw rate of just 26.3 percent, which is slightly better than the previous best value of 27.5 posted by the 2019 Final Four team.
The current values for the other two defensive factors are not as good. For effective field goal defense, the current Spartans squad is allowing opponents to shoot 46.5%, which is slightly worse than the median value of 45.8%.
As for the final factor, creating turnovers, the 2022-23 teams is only performing at a rate of 15.2 percent, which is in the bottom quartile of Michigan State teams. This have never been a strong emphasis of a Tom Izzo coached team, and while this performance is historically not very good, it is similar to the values posted by each of the past seven Spartan teams.
In Michigan State's most recent performances, two of the values were basically right on the year-to-date averages. The Spartans held both Oakland and Buffalo to around 46% effective field goal shooting and to an offensive rebounding rate of around 24%.
The Spartans also did a very good job of reducing fouls over the past two games. Oakland and Buffalo posted a free throw rate of just 15.2% and 17.5%, respectively.
Defensive turnovers were a mixed bag. The Spartans posted a very low turnover rate of 12.3% against Oakland, but improved against Buffalo to post a respectable (and historically average) rate of 18.7%.
Add it Up
So who are the 2022-23 Michigan State Spartans? The free throw factors suggest that they are a team who does foul much, but who also does not get fouled. That would seem to cancel out, but I am not convinced that this trend will continue into Big Ten play. Officiating tend to stabilize (for better or worse) in conference play.
The Spartans are a team who is not turning the ball over much, but they are also not creating second shots through offensive rebounding. On defense, Michigan State is not causing many turnovers, but they are cleaning the defensive glass. These factors are also canceling out.
So, at the end of the day, the fate of the Spartans will largely depend on the most important factor: shooting. Right now, Michigan State is slightly below average (historically) on both offensive and on defense in effective field goal percentage.
If the Spartans plan to see their star ascend in 2023, they need to improve in these two areas. They will need to shot the ball better (especially on two-point shots) and they will need to defend a little better. Time will only tell much improvement will actually happen.
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