Editor’s note: All statistics used for this article are courtesy of CBBAnalytics.com and are up to date following Duke’s Wednesday game against Louisville. Only in-conference ACC games are considered in this analysis.
Duke seems to have put it together heading into the final stretch of its season. After a 5-3 start, the Blue Devils have won 17 of their last 20 games and clinched a double-bye in the ACC tournament. So who’s to thank for the recent success?
From the proverbial “eye test,” it seems that Jared McCain has propelled the Blue Devils’ momentum. The freshman guard has dazzled the Duke faithful with his tough layups, effective rebounding and lights-out shooting. Box scores also view the freshman favorably — he averages 13.6 points and 4.9 rebounds on a 41.8% rate from 3-point range. By all accounts, he is one of Duke’s best players and one of the most dynamic freshmen in the country.
However, venturing into the land of advanced statistics — categories like true shooting, free-throw rate and turnover percentage — paints a different picture of the Sacramento, Calif., native. In particular, the net rating statistic paints McCain as a negative for the Blue Devils.
Is one of Duke’s seemingly most important players truly a detriment to the team, or is there more to this story?
What is net rating, and what does it say about McCain?
Net rating is the difference between offensive and defensive rating, which measure a team’s points scored and allowed, standardized per 100 possessions, respectively. Duke has an in-conference offensive rating of 118.4, meaning that it scores, on average, 118.4 points for every 100 offensive possessions. Likewise, the Blue Devils’ 103.8 defensive rating means that the team allows an average of 103.8 points per 100 defensive possessions. When subtracting the two, Duke sports a net rating of plus-14.6, which ranks in the 93rd percentile in Division I.
An important note: Net rating is not to be confused with the NCAA Evaluation Tool, also known as NET ranking, which ranks teams based on their wins and losses scaled to level of competition.
When separating a team’s minutes into times when a player is on or off the court, a player’s impact on net rating can be clearly shown. For instance, senior captain Jeremy Roach has a plus-20.5 on-off net rating in conference play, by far the highest mark for the Blue Devils. This implies that Duke scores 20.5 more points per 100 possessions when Roach is on the court.
Surely McCain, with his shooting prowess and motor, would place highly in this statistic, right?
Not quite. The freshman has a minus-12.4 on-off net rating this season, the worst of any Blue Devil who has played at least 135 minutes. If considering just ACC games, McCain’s net rating plummets to minus-20.9. He appears as a negative for Duke on both offense and defense — in ACC play thus far, the Blue Devils are 4.2 points worse on offense and 16.7 points worse on defense (both per 100 possessions) when he plays compared to when he sits.
The stats say that the Blue Devils fare better — much better, in fact — when McCain is off the court. So what’s really going on?
How McCain performs with and without Foster, Duke’s veterans
Net rating is a statistic influenced by several factors, including the teammates that one plays or doesn’t play with. McCain’s net rating in particular has varied heavily depending on his supporting cast, especially in the backcourt.
McCain and fellow freshman guard Caleb Foster have frequently appeared on the court together; the Blue Devils have featured lineups with both freshmen on the floor for nearly half of their ACC minutes. That figures to change soon, however, with Foster sidelined indefinitely with an ankle injury suffered during Duke’s loss at Wake Forest. As such, it’s worthwhile to compare how McCain has fared with or without Foster. Figure 1 shows Duke’s net rating when McCain and Foster are in or out of the lineup.
McCain has also racked up significant playing time with veterans like Roach and Tyrese Proctor. In fact, the Blue Devils have played just two minutes without at least one of the three guards on the floor. Figures 2 and 3 show Duke’s offensive and defensive rating, respectively, when McCain, Roach and Proctor are in or out of the lineup against conference foes. A lower defensive rating corresponds to better defense (i.e. less points allowed).
Another way to analyze this trio’s impact is their ball security when they rotate in and out of the lineup. Figure 4 displays the Blue Devils’ turnover percentage with the trio on or off the court. A lower percentage indicates better ball security on offense.
As the graphs show, Duke struggles on defense when McCain is paired with only one veteran guard, but has done well when the trio plays together or when McCain rests. When Roach and Proctor both play with McCain out, the Blue Devils hold opponents to an effective field-goal percentage of 31.4% and allow just 77.6 points per 100 possessions. Both metrics would be in the 100th percentile in Division I this season. Proctor is certainly a strong on-ball defender by himself, but his pairing with Roach in the backcourt appears to limit opposing guards’ precision as shooters. While steals are by no means a holistic indicator of defensive ability, Roach ranks in the 73rd percentile for steal percentage; he is an ideal ball-hawk on the perimeter.
When McCain, Roach and Proctor play together, Duke loses a bit of its tenacity on defense, but still proves strong on that side of the ball. In 208 minutes of that trio playing together, the Blue Devils have allowed a defensive rating of 94.2, a strong mark. It’s worth noting that the aforementioned Roach-and-Proctor-without-McCain lineup has played just 66 minutes.
When looking at this trio from an offensive perspective, it’s clear why McCain has garnered the playing time he has. Duke’s offensive rating is better when McCain plays with just Roach (118.6) or just Proctor (113.3) compared to when Roach and Proctor play without McCain (112.3). When head coach Jon Scheyer opts to play all three guards, the results are even better — a 119.8 offensive rating, which would be by far the highest mark among ACC teams. It’s not hard to see why this lineup succeeds on offense — it has two above-40% shooters from 3-point range in Roach and McCain, and Proctor serves as an excellent facilitator, with his assist-to-turnover ratio ranking in the 92nd percentile for guards nationally.
Overall, the three-guard combo has produced a plus-25.6 net rating, somewhat below the Roach-Proctor combo but with better offensive production. Additionally, McCain appears to provide strong ball security in the backcourt; the three-guard lineup has a turnover percentage of 15.3% compared to a poor 20.9% when just Roach and Proctor play.
Is there a “best” lineup for McCain?
Calling McCain a negative for the Blue Devils solely because of his on-off net rating would be inaccurate. In terms of effective field-goal percentage, the freshman ranks in the 91st percentile of guards nationally this season. His hot shooting has translated to objectively strong offense — Duke sports an offensive rating of 117.6 when he’s on the court, good for the 93rd percentile.
However, analytics do point to a defensive weakness in McCain’s game. Duke is 16.7 points better on defense per 100 possessions when McCain is off the court compared to when he plays. To counter this, the three-guard lineup of Roach, Proctor and McCain has proven strong. The two veterans’ on-ball defensive skills, some of the best on the team, combined with their facilitation on offense can help bring out the best of McCain, a shooter and slasher with a strong off-ball impact. While the lineup sacrifices some defense, it more than makes up for it on the offensive end, contributing to a strong backcourt for Scheyer to play as Duke gets into its most competitive stretch of the year.
On the other hand, according to the numbers, the Foster-McCain pairing has been a negative for the Blue Devils on both ends of the floor. The duo seems to play best when one player is not on the court. If and when Foster returns from his ankle injury, Scheyer may choose to rotate the two freshmen, as he has shied away from four-guard lineups during conference play.
Net rating doesn’t tell the full story of McCain’s abilities and production on the court. By all accounts, he is one of the Blue Devils’ most valuable players and will be a large part of their offensive attack through March. But, advanced statistics point to the importance of Roach and Proctor for both McCain and Duke as a whole, especially on the defensive side of the ball.
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