NBA

NBA PM: The Truth About Rookie Defense

Everyone talks about how rookies struggle on defense, but those criticized most often aren’t as bad as you think.

Alan Draper profile picture
Sports Editor
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The Truth About Rookie Class Defense

As the NBA swings to the back part of the season and teams race to the finish line and the postseason in some cases, more and more focus will shift toward predicting the end-of-season awards. One of the more interesting races to watch will be the NBA’s Rookie of the Year award. Minnesota Timberwolves big man Karl-Anthony Towns is the frontrunner, as he’s having an impressive and consistent rookie campaign that couldn’t have been scripted any better. Then, there is New York Knicks sensation Kristaps Porzingis, who has exceeded everyone’s pre-draft expectations. Looming in the third chair is likely Philadelphia 76ers center Jahlil Okafor.

No name in the rookie class is more polarizing these days than Okafor, whether it’s his over-hyped and overblown off-court antics, the perception that he’s the NBA’s worst defender or just a general dislike of a throwback big man who thrives in the low-post.

The off-court stuff is what it is. It’s never nearly as bad as it seems, but it’s certainly not a good look while campaigning for something (not that players actively try to get votes for such things).

The throwback style of play is what makes Okafor so special. He is arguably one of the most skilled low-post players in the game right now and he’s just a baby in his NBA career.

Which brings us back to the defense issue.

Before we get too far into this, it is important to say that almost no team in the NBA plays man-on-man defense. So trying to judge a player’s defensive prowess based on how he guards his man neglects that players have rules for how they guard that man based on the team defense. If the point guard misses his assignment, is that on the center for not being there to catch the play?

No one is going to look at Okafor and say he’s the next great defender. However, the stats say he’s not nearly as bad as some would paint him.

The NBA’s new SportVu camera technology allows for the tracking of things in a much more granular way. While there isn’t a great statistic to track defense, one that’s very credible is Defensive Field Goal Percentage, or what a player scores while being defended by another player. When you compare that percentage to a player’s average, you can see if the defending player is at least holding the offensive player to their average.

In looking at the rookie class, there were some interesting things that surfaced defensively, as measured by Defensive Foul Goal Percentage. Chicago Bulls forward Bobby Portis may be the best rookie defender who has played more than 30 games. Portis is holding offensive players to 37.8 percent from the field, while those same players are averaging 44.8 percent on the season.

Here are the top 20 rookies by Defensive Field Goal Percentage, based on 30 or more games played:

Player  Age  GP  DFG%  FG%  DIFF
Bobby Portis  21  36  37.8  44.8  -7
Kristaps Porzingis  20  60  42.4  46.6  -4.2
Nikola Jokic  21  56  45.6  48  -2.4
Jerian Grant  23  51  41.6  43.3  -1.7
Emmanuel Mudiay  19  45  42.9  44.2  -1.3
Myles Turner  19  37  45.3  46.1  -0.8
Justise Winslow  19  55  43.1  43.9  -0.8
Nemanja Bjelica  27  45  44.5  45  -0.5
Karl-Anthony Towns  20  58  46.6  46.9  -0.3
Jahlil Okafor  20  53  47.6  47.7  -0.1
Willie Cauley-Stein  22  42  45.8  45.4  0.4
Larry Nance Jr.  23  45  47.2  46.7  0.4
Trey Lyles  20  51  46.8  45.8  1.1
Lamar Patterson  24  32  45  43.8  1.2
Frank Kaminsky  22  57  46.6  45  1.6
Boban Marjanovic  27  33  49  47.4  1.6
Stanley Johnson  19  56  45.5  43.7  1.7
D’Angelo Russell  20  57  46.6  43.9  2.7
Rashad Vaughn  19  50  46.4  43.3  3.2
Devin Booker  19  50  47  43.7  3.3

The next part to look at is distance to the basket. When you measure Defensive Field Goal Percentage within 10 feet of the basket, things change a little. Within 10 feet, the top rookie defender ends up being Knicks forward Kristaps Porzingis; he is holding opposing offensive players to 47.5 percent when their usual average is 55 percent.

Here are the top 15 rookies by Defensive Field Goal Percentage within 10 feet, based on 30 or more games played:

Player  GP  DFG%  FG%  Diff%
Kristaps Porzingis  60  47.5  55  -7.5
Boban Marjanovic  33  49  54.8  -5.8
Nikola Jokic  56  50.3  55.7  -5.3
Jahlil Okafor  53  50  54.8  -4.8
Karl-Anthony Towns  58  50.2  54.3  -4.1
Bobby Portis  36  50.4  53.9  -3.5
Myles Turner  37  50.7  53.9  -3.2
Frank Kaminsky  57  53  53.8  -0.8
Justise Winslow  55  53.2  53.4  -0.2
Willie Cauley-Stein  42  53.5  53.4  0.1
Nemanja Bjelica  45  54.1  53.9  0.2
Trey Lyles  51  55  54.4  0.5
Larry Nance Jr.  45  58.9  56.6  2.3
Jerian Grant  51  56.7  54.3  2.4
Lamar Patterson  32  59  55.6  3.4

The last part is closer to the rim, as measured by six feet or closer. When you look at Defensive Field Goal Percentage within six feet, the top rookie defender is again Porzingis, who is holding 49.6 percent on an average of 60.1 percentage. That’s a full 10.5 points below his oppositions’ average.

Another variable to consider is, how frequently are they defending a player at that distance? In the case of the six-feet sample, Indiana’s Myles Turner is seeing players within six feet 54.5 percent of the time, which makes his 50.4 percent Defensive Field Goal percentage on a 58.6 percent average all the more impressive.

Here are the top 15 rookies by Defensive Field Goal Percentage within six feet, based on 30 or more games played:

Player  GP  FREQ  DFG%  FG%  Diff%
Kristaps Porzingis  60  45.20%  49.6  60.1  -10.5
Boban Marjanovic  33  47.70%  50.7  59.1  -8.3
Myles Turner  37  54.50%  50.4  58.6  -8.1
Nikola Jokic  56  46.20%  53.7  61.2  -7.5
Jahlil Okafor  53  46.30%  53.8  60  -6.2
Karl-Anthony Towns  58  51.30%  54.5  59.6  -5.1
Richaun Holmes  42  38.80%  54.8  58.9  -4
Willie Cauley-Stein  42  30.70%  55.1  58.9  -3.8
Frank Kaminsky  57  34.10%  56  58.5  -2.5
Bobby Portis  36  36.60%  57  59.3  -2.3
Emmanuel Mudiay  45  26.30%  60.6  59.7  0.8
Justise Winslow  55  24.50%  60.3  59.4  0.9
Trey Lyles  51  33.60%  60.7  59.8  0.9
Stanley Johnson  56  21.20%  62.2  60.8  1.4
Nemanja Bjelica  45  41.10%  60.8  59.3  1.6

If you look at each chart, you’ll notice that Okafor ranks in the top 10 in total Defensive Field Goal Percentage among rookies. He ranks in the top five in both categories closer to the rim.

It’s safe to say Okafor has a lot of room to improve compared to the other veteran players in the NBA, but compared to his rookie class peers – including Towns – Okafor isn’t nearly as bad a defender as he’s often made out to be. Yes, he needs to do a better job getting in position at times (like all young centers), but when he’s actually guarding his man, he’s serviceable.

Also, some of Okafor’s defensive issues have more to do with the island he gets placed on, which wouldn’t occur on a better defensive team. Looking at the numbers and the situation he has been put in, it’s unfair how much hate Okafor has had to endure about his defense.

As the 20-year-old Okafor matures and his Sixers team matures defensive, both sides should see their numbers go up.

Some may argue the premise based on what they see on the floor; however, the stats paint a very different picture.

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Alan is an expert gambling writer who works as one of the chief editors for Basketball Insiders. He has been covering online gambling and sports betting for over 8 years, having written for the likes of Sportlens, Compare.bet, The Sports Daily, 90min, and TopRatedCasinos.co.uk. His particular specialisms include US online casinos and gambling regulations, and soccer and basketball betting. Based in London, Alan holds an MA in English Literature and is a passionate supporter of Chelsea FC.

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