After making just 1.17 3-pointers / 40 minutes at a rate of 29.7% through his first two collegiate campaigns, Justin Jackson has improved those numbers to 3.17 and 38.7% after 17 games of his junior season. Both his 3-point volume (per-40) and efficiency have significantly increased season-over-season—a testament to the feedback he received from NBA scouts, and the hard work he put in all summer. But just how rare is it for a Tar Heel to make the type of perimeter improvement that Jackson has this year? Let’s dig deeper into the data to answer that question.
For the sake of this analysis, we’ll look at two primary numbers: 1.) 3-point percentage (efficiency) and 2.) pace-adjusted 3-point attempts per 40 minutes (usage/volume). In Jackson’s case, his season-by-season marks in these metrics are:
Justin Jackson's year-by-year 3Pt improvement:
FR: 30.4%, 3.69 3PtA/40 (pace-adjusted)
SO: 29.2%, 4.19
JR: 38.7%, 7.62
— Adrian Atkinson (@FreeportKid) January 9, 2017
Using these two concepts of 3-point proficiency, we can create a metric called Points Above Replacement Shooter per 1,000 Minutes—or PARS/1000. Since 2002, the national average has hovered between 33.9% and 35.1%. The average for those seasons in 34.5%. For the sake of this analysis, we’ll consider a “replacement-level” shooter to be one who connects on 30% of his 3s. While that number is somewhat arbitrary, it doesn’t make a difference for the sake of the rankings/ordering. Alternatively, we could use the concept of an average shooter here rather than a replacement-level one, too. 1,000 minutes is used because a.) it’s a round number, and b.) it’s about the number of minutes an average collegiate starter will play in a season (35 games at 26.6 MPG).
Jackson’s PARS/1000 this season can be computed as follows:
- 7.62 3-pointers per 40 minutes –> 190.5 3-pointers per 1,000 minutes
- a replacement-level shooter would score 171.5 points on those attempts (190.5 * 0.300 * 3)
- Jackson would score 221.2 points on those attempts (190.5 * 0.387 * 3)
- thus, Jackson has a PARS/1000 of 49.7 (221.2 – 171.5)
As a sophomore, Jackson’s PARS/1000 was actually negative (since he fell slightly below the 30% mark) at -2.5. Thus, his season-over-season change in this metric was (49.7 – (-2.5)) = +52.2. So how does that mark compare historically to other UNC shooters? Let’s take a look at the table below:
The major assumption used here is that a player must log at least 10 minutes/game in each of the seasons for which the PARS/1000 change is being measured. This will ensure that we’re only including players who were in the rotation in both years of the comparison. It excludes the freshman-to-sophomore leaps of some memorable UNC shooters like Hubert Davis, Donald Williams, Shammond Williams (and Kenny Williams this season), as well as Wes Miller’s sophomore-to-junior jump and Pearce Landry’s junior-to-senior one. If we were to raise the minutes/game threshold to 15, Jackson would actually climb to No. 2 on the list behind Okulaja (Hairston and Curry played 13.0 MPG as freshmen, McDonald played 10.3, and Graves (prior to his suspension) played 11.2 as a sophomore).
The players on this list can be split into three primary buckets:
- Those who improved both their 3-point volume and efficiency significantly. This includes (at least to date) Jackson and Berry this season. It also includes Britt’s jump between his freshman and sophomore seasons (a time period in which—stop me if you’ve heard this one—he actually changed shooting hands!). Others on this list include McDonald, Okulaja, Graves, Stackhouse, Cota, Paige, and Jawad Williams.
- Those who improve their 3-point efficiency significantly. This group includes Hairston, Curry, Felton, Calabria, Bullock (twice!), Davis, Boone, Green, Lawson, and Donald Williams. For some on this list (notably, Curry, Calabria, and FR-to-SO Bullock), 3-point volume actually went down (as part of a volume-efficiency trade-off). For some (Felton, Boone, Green, D. Williams) it went up slightly. For some (Hairston, SO-to-JR Bullock, Davis, Lawson), it stayed nearly the same. In all cases, it was the increase in 3Pt% rather than an increase in the volume that was driving the improvement.
- Those who increase their 3-point volume significantly while maintaining a high percentage. This is the rarest type on the list, including just Fox, Bucknall, Scott, and Noel. Scott moved from point guard as a freshman to off the ball (alongside Felton) as a sophomore. Noel’s volume increased to help compensate for the losses of Felton, McCants, Scott, and Jawad/Marvin Williams from the ’05 champs. Fox and Bucknall likewise stepped up as upperclassmen to help fill perimeter voids (the loss of Ranzino Smith in Bucknall’s case, and the losses of Lebo/Bucknall in Fox’s).
In the offseason, I’ll play around a little more with this data (career PARS/1000 leaders, categorizing UNC’s historical 3-point shooters into buckets by career shooting progression, etc.). For the remainder of this season, the ability of Jackson and Berry to maintain their places on this list will help to determine just how special Carolina’s season ends up being. The Heels will need both to continue being high-volume, high-efficiency options from behind the arc.
An interesting aside about Jackson’s 3-point shooting in 2017: he continues to be significantly more effective from the left side of the floor than the right side from the perimeter (and as a penetrator too, actually; his floater percentage from the left paint is much better than from the right paint). Here are his 3-point splits by shot location:
- right corner: 25.0% (2-8)
- right wing: 20.0% (6-30)
- top of the key: 44.4% (8-18)
- left wing: 51.3% (20-39)
- left corner: 45.5% (5-11)
Or, summing those up: 21.1% from the right side (on 38 attempts) and 50.0% from the left side (on 50 attempts). The top of the key was right about in the middle percentage-wise (and, you know, shooting-wise) until Jackson hit 2-of-2 there against NC State to bump that percentage until the mid-40s. Just something to keep an eye on as the season progresses.