Franalysis: Getting to the Free Throw Line Has Been the Key to Iowa's Offensive Success During the McCaffery Era

By houksyndrome on January 4, 2021 at 4:20 pm
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© Jeffrey Becker-USA TODAY Sports
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Let's start off 2021 on a good note by examining Iowa MBB's offensive performance during the McCaffery Era.  Let's do a statistical comparison between Iowa's offense and its Big Ten peers to examine the narrative that Iowa has generally been a good offensive team under Fran.  We'll look at the particular areas of offense where Iowa has excelled over the last decade.  Lastly, we'll compare the offensive development of Fran's players over the course of their careers with that of other Big Ten players.  There are some interesting trends for us to dig into further..

Here's how Iowa has performed offensively, relative to its Big Ten peers, in a wide range of statistical categories.  The statistics are:

  • adjusted offensive efficiency (AdjO, points per possession adjusted by the quality of defenses that Iowa faces)
  • effective field goal percentage (eFG%, (2 pointers made + 1.5 * 3 pointers made)/field goal attempts)
  • turnover percentage (TO%, Turnovers/Possessions) 
  • offensive rebounding percentage (OR%, Offensive Rebounds/Missed Shots)
  • free throw rate (FTR, Free Throw Attempts/Field Goal Attempts)
  • shooting percentage on two pointers and three pointers (2P% and 3P%, respectively)
  • shooting percentage on free throws
Offensive Performance during the McCaffery Era
  2011 (11 teams) 2012 (12 teams) 2013 (12 teams) 2014 (12 teams) 2015 2016 2017 2018 2019 2020 Average Finish Ranking
AdjO 11 8 7 3 4 5 6 3 3 1 5.7 4th
eFG% 11 8 9 5 10 7 5 4 3 4 7.3 8th
TO% 11  6 7 4 5 2 9 11 7 8 7.6 7th
OR% 4 6 4 1 2 5 5 2 7 5 4.4 3rd
FTR 5 3 3 2 3 9 4 6 1 4 4.3 3rd
2P% 10 9 8 5 10 9 8 6 5 3 7.9 8th
3P% 11 4 11 5 11 4 4 4 3 4 6.7 8th
FT% 10 5 2 5 5 8 10 11 3 4 6.8 4th

Iowa has been successful at the offensive end of the floor during Fran's tenure.  Their average ranking in adjusted offensive efficiency is 5.7th place in the Big Ten, which is actually the fourth best ranking among Big Ten teams (only Michigan 4.5, Michigan State 4.7 and Purdue’s 5.2 have better average rankings).  So the that Fran’s teams are good on offense is not an illusion or any sort of internet/echo chamber-driven narrative.  His teams really do tend to be very good on offense.

If we break down the component stats, we can see exactly why Fran’s teams are successful on that end of the floor.  It’s not due to field goal shooting percentage.  In aggregate, his teams have been the 8th best shooting team in the Big Ten in effective field goal percentage, which tracks accuracy on two point shots as well as accuracy on three point shots.  His teams are also average at turnover avoidance (7th in the Big Ten).  His teams have been good offensively, relative to the rest of the Big Ten, for primarily three simple reasons:  offensive rebounding, the ability to get to the free throw line (i.e. free throw rate, FTA/FGA) and free throw shooting accuracy (FTM/FTA).  Iowa ranks 3rd, 3rd, and 4th, respectively, in those three statistical categories during Fran’s tenure at Iowa.

Have you ever wondered how much Fran's players improve on offense relative to other Big Ten players?  I have and over the last 18 months or so, I've been gradually putting together a data set to assess the offensive improvement of Fran's players and compare that with their Big Ten peers.  To be included in my data set, a player had to play at least three seasons with a Big Ten program and had to play as either a Freshman or redshirt Freshman (i.e. no incoming transfer players were included).  I aimed for a cohort of at least twenty players for each current Big Ten team and went back over time, looking at all players for that team, until I could fill out the cohort.  All of these statistics are derived from Ken Pomeroy's website.  In each graph, Iowa is shown in red while all of the other Big Ten teams are shown in gray-scale.  

Many years ago, a basketball analyst named Dean Oliver (no relation) developed a metric of offensive efficiency for individual players called “O Rating”.  The exact formula is quite complicated as it rolls effective shooting percentage, assists, turnovers, free throws and offensive rebounds together into a single metric.  I’ll give you some sample O Ratings for players that you are familiar with so you have a frame of reference for these numbers.  Cully Payne was 86 in his first and only season as a Hawk.  Mike Gesell was 99 as a freshman.  Guys like Basabe and McCabe were around 110 as upper classmen.  Garza was 117 last year (a very high efficiency for an extremely high usage player).  Zion Williamson was 129.

Here is how O Ratings for Fran Era players stack up with their Big Ten peers as their careers progress (median values for each team).

Average Offensive Rating for Big Ten Players

As you can see, the O Ratings of Iowa’s players roughly follow the same trajectory as the rest of the Big Ten.  Iowa’s players have a median O Rating of 100.35 as freshmen, which is a tick above conference average (98.0), and they improve to 110.9 by the time they are seniors, which is also slightly above average (109.2).  The average Big Ten player improves by about 11.2, while the average Hawkeye improves by about 10.6 during the Fran era.  So, in terms of improvement, the Hawkeyes are roughly average, as can be seen in the following graph which depicts O Rating improvement.

Offensive rating improvement for Big Ten players

The story really gets interesting, though, when we look at which aspects of offensive performance improve and which do not.  I first want to draw your attention to shooting accuracy on two pointers.  The graph below shows the overall shooting percentage on two pointers (2PM/2PA for each team’s entire cohort).  

Two point shooting accuracy for Big Ten players

There are a few things that jump out.  First, Iowa’s freshmen are second in the conference in two point shooting accuracy at 50.9%, behind only Ohio State.  However, by the time they are seniors, Iowa’s players are slightly below average on two pointers (49.7% vs 50.2%).  If I graph the change in two point accuracy during each player’s career, the result is even bleaker.

Two point shooting improvement for Big Ten players

There is a very clear tendency for Big Ten players to improve their accuracy on two pointers by about 2.5%.  Ken Pomeroy has a great article for The Athletic where he does the same analysis for a larger group of players (i.e., all D1 players who were seniors in 2019) and found a two point accuracy improvement of about 4% from Freshman to Senior year.  Yet Fran’s players at Iowa do not improve their two point accuracy.  If anything, they get worse.  Michigan State is the only other program in my dataset with a lower two point accuracy as seniors than as freshmen and MSU’s falloff may be an artifact of Ward and Tillman leaving for the NBA after their junior seasons.  Regardless of the reason for MSU’s two point shooting, Iowa’s lack of two point shooting improvement is certainly an outlier both with respect to the rest of the Big Ten as well as the overall NCAA.

Is Fran just uniquely terrible at teaching guys to shoot?  No. I don't think that's the explanation here.  Rather, Iowa's primary offensive strategy seems to be to draw fouls and get to the free throw line.  Iowa's two point shooting percentage suffers because they're trying to draw contact and the refs don't call 100% of the fouls that occur.  Here is the free throw rate (free throw attempts divided by field goal attempts) for these same cohorts of players.  Behold!

Free Throw rate for all Big Ten players

As you can see, Iowa's cohort is a clear outlier in that statistical category, especially by the time they're seniors.  Things get even more striking if we focus specifically on how players' free throw rates change during their careers.

Free Throw Rate improvement for Big Ten players

The free throw rate of Iowa's players improves by 11.3 during their careers and no other Big Ten program is even as high as 5.  On average, the free throw rates of these cohorts actually decreases by about 0.7 from Freshman to Senior year.  Iowa is over two standard deviations from the mean in terms of FTR improvement.  I think this is real and I think it is coached.  

If drawing contact and getting to the line is something that Fran emphasizes, then perhaps similar trends regarding two point shooting accuracy and free throw rates can be found in his players at Siena and UNC-Greensboro, so I generated an identical cohort of players from those two schools (pooled together, shown in blue).  Here is what the FTR for Fran's players was like at Siena and Greensboro:

Free Throw rate for all Big Ten and UNCG/Siena players
If we focus on FTR improvement from Freshman to Senior season, it looked like this:
Free Throw rate improvement for all Big Ten players and UNCG/Siena players

That's right, Fran's players at UNC-Greensboro and Siena collectively improved their free throw rate by a preposterous 33.  Fran's UNC-Greensboro and Siena players' accuracy on two pointers also dropped from 49.4% as freshmen to 47.4% as seniors.  When we combine some of these findings on Fran's offense (low two point accuracy + high number of free throws attempted) with Fran's defense (high two point accuracy allowed + low number of free throws), I think we gain insight into Fran's basketball philosophy:  don't foul them and get them to foul us.

Of course, getting to the line means nothing if you can't actually make the free throws once you get there.  Here's how Iowa does at converting free throws.

Free Throw accuracy for all Big Ten players

Iowa's cohort of players was actually at the top of the league by the time they were seniors in free throw shooting accuracy.  I must say that surprised me a bit.  If we focus specifically on improvement from Freshman to Senior seasons, Iowa still comes out quite well:

FT Accuracy improvement for all Big Ten players

Lastly, we should examine how Fran’s players develop from three point range:

Three point shooting accuracy for all Big Ten players

So these numbers aren’t great.  As Freshmen, Iowa’s players shoot 34.8% from three point range which is a bit better than average for Big Ten freshmen.  However, the average Big Ten player’s three point shooting accuracy improves to about 37% by the time he’s a senior (about a 3% improvement), whereas it stays flat at 34.7% for Iowa’s seniors.  You can get an idea of Iowa's (lack of) three point accuracy improvement compared to their peers here:

Three point shooting accuracy improvement for all Big Ten players

Ken Pomeroy’s article reported a ~2% increase in three point shooting accuracy in the larger cohort of players that he tracked.  I don’t think that Iowa's lack of improvement from three point range is due to Iowa attempting to draw fouls.  Shooting fouls on three point shots are relatively rare and there generally isn’t much contact on three point attempts.  Fran’s players at Siena also did not improve from three point range over the course of their careers (35% as Freshmen, 33% as Seniors).  So this is an area that Fran might want to have a look at.  He is clearly a good offensive coach whose success revolves around creating high-efficiency scoring opportunities at the free throw line.  However, the three point line is also a high-efficiency area and, although we’ve certainly had some great shooters during his time here (especially on the current team), it looks to me like he could stand to tweak the way he coaches three point shooting.

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