Using Individual Matchup Data to Evaluate Defense in the NBA

Stephen Lew – USA TODAY Sports

The NBA’s recent statistical revolution has had a profound impact on the way we view and play the game. However, a statistical approach to evaluating a player’s performance is still quite imperfect, especially on the defensive side of the ball. There are many different metrics out there which attempt to accurately portray a player’s aptitude on defense. Certain metrics use shooting data, others use box score numbers, while recent innovations are based around plus-minus figures from lineup data.

However, all of these metrics still fall short. The shooting data used for the DRAYMOND rating doesn’t account for the quality of a player’s opponent. It must be easier to contain Andre Roberson than LeBron James, right? And while basic box score stats are easy to derive and analyze, they don’t tell you much. Stephen Curry led the league in steals in 2016, but I don’t think anybody would argue that he’s an elite perimeter defender. Finally, many plus-minus metrics struggle with attribution and collinearity. Players who play a small role on a good team are often given too much credit because the team happens to be playing well even if they are not the most important cause of that success. This can be partially remedied by looking at long-term data (i.e. multi-year samples) but that isn’t always a convenient possibility.

Of course, while none of these metrics are anywhere close to flawless, they are certainly not useless. However, the lack of an extremely reliable all-in-one defensive stat left me wanting to test a relatively untouched idea just for the sake of experimentation. Could we use individual defensive matchup data to evaluate defensive performance?

The NBA made their defensive matchup data available beginning in 2018. The numbers used Second Spectrum’s player tracking system to determine which defender guarded each offensive player for the majority of each possession. For instance, we could compare James Harden’s performances while guarded by Stephen Curry versus Klay Thompson.

The basis for a defensive metric would be to determine the number of points a defender would have been expected to directly concede over the course of a season based on players they matched up against. In other words, holding Stephen Curry to 20 points over 100 possessions is weighted greater than containing Rajon Rondo to the same output because Curry would be expected to score more points than Rondo. The actual metric looks at more deeper numbers than just points and possessions (how many shots they took, how many of those shots were three-pointers, how many turnovers did they commit compared to their average turnover rate, etc), but the fundamental concept is the same.

Using a Python script to comb through every single matchup in the NBA over the past two years, we can determine how many points a defender saved compared to the expectation in each matchup. Finally, we average this number and scale it to 100 possessions in order to arrive at our result.

Listed below is each qualifying NBA player’s Defensive Value (DVAL) over the past two seasons. The number is an estimate of the number of points each player stopped from being scored by their offensive matchup per 100 possessions.

PlayerPositionPossessionsDVAL
Rudy GobertC88383.30
Aron BaynesC45392.61
Jrue HolidaySG111572.57
Al HorfordC84312.53
Luc Mbah a MoutePF31202.45
Jusuf NurkicC83122.24
Steven AdamsC106692.22
Bruce BrownSG29112.08
Jaylen BrownSG80922.05
Eric BledsoePG94502.04
Clint CapelaC86431.99
Anthony DavisC96431.98
Thabo SefoloshaSF28061.96
Kyle AndersonSF64101.89
Derrick FavorsC78601.87
Ben SimmonsPG113051.83
Kyle LowryPG96361.78
Giannis AntetokounmpoPF103831.71
Brook LopezC85321.70
Darren CollisonPG83381.67
Draymond GreenPF90371.65
Al-Farouq AminuPF88591.59
Semi OjeleyePF35041.56
Gordon HaywardPF39041.52
Alex CarusoPG22771.52
Jonas ValanciunasC57651.51
LaMarcus AldridgeC103231.51
Marc GasolC95361.48
Derrick RosePG37921.44
Kosta KoufosC37631.44
Terry RozierPG75851.43
Stanley JohnsonSF62791.42
Jonathan IsaacPF50241.4
Klay ThompsonSG105641.38
Bam AdebayoC65251.36
Hassan WhitesideC61341.35
Myles TurnerC79411.34
James HardenPG107721.34
Ekpe UdohC22891.32
Kawhi LeonardSF45801.26
Paul GeorgeSF116761.26
Fred VanVleetPG65281.21
Pascal SiakamPF85521.19
Blake GriffinPF91831.19
DeAndre JordanC91571.18
George HillPG62731.18
Marcus SmartSG76521.17
Aaron GordonPF90891.17
Goran DragicPG67511.17
Lance ThomasPF42461.16
Andre IguodalaSF66131.16
Thaddeus YoungPF101801.13
Rodions KurucsSF28001.13
Richaun HolmesC39801.13
JaVale McGeeC48701.12
Dewayne DedmonC64461.11
Nikola VucevicC84391.1
Gary HarrisSG77941.10
John WallPG52241.09
Tyson ChandlerC42161.07
Tyler ZellerC23451.06
Kemba WalkerPG113591.05
T.J. McConnellPG64791.04
Josh RichardsonSG103591.03
Shai Gilgeous-AlexanderPG45581.03
Shaun LivingstonPG42871.02
Boban MarjanovicC21261.01
Derrick Jones Jr.SF28181.00
Justise WinslowSF72540.99
Avery BradleySG67810.99
Joel EmbiidC83600.98
Dwayne BaconSG30200.98
Khem BirchC24640.97
Mike ConleyPG53580.97
Andrew WigginsSF112210.96
Pau GasolC43400.95
Lonzo BallPG66930.95
Victor OladipoSG74050.93
Danny GreenSG80680.93
Dwight HowardC55000.93
Tyreke EvansSG59900.92
Josh HartSG66650.92
Ivica ZubacC30570.92
Chris PaulPG73890.91
Seth CurrySG27860.91
Dorian Finney-SmithSF49440.91
Wes IwunduSF45350.89
Malcolm BrogdonSG66600.88
Robin LopezC66990.87
Marcin GortatC56720.87
Cory JosephPG85730.83
Raymond FeltonPG33800.83
Tomas SatoranskyPG76030.78
Cody ZellerC38590.74
Rodney McGruderSG37740.72
LeBron JamesSF102750.72
Jimmy ButlerSF87690.70
Shaquille HarrisonPG37100.70
James JohnsonPF61780.68
Rondae Hollis-JeffersonSF64500.68
Jeff GreenPF81210.66
Norman PowellSG44780.66
Delon WrightPG63230.65
Treveon GrahamSG36350.65
Omri CasspiSF25760.64
OG AnunobySF58310.64
Luke KornetPF22240.62
Michael Kidd-GilchristPF62150.61
Harrison BarnesSF105560.61
Donovan MitchellSG104850.61
Anthony TolliverPF57250.55
Ish SmithPG65670.55
Danilo GallinariSF56200.54
Joe InglesPF102360.53
Domantas SabonisC73030.50
Jeff TeaguePG72640.48
Buddy HieldSG95520.48
Paul MillsapPF60510.46
Patrick PattersonPF42220.44
Sindarius ThornwellSG31080.43
Ersan IlyasovaPF61450.43
Josh OkogieSG37020.42
Eric GordonSG87090.42
Ricky RubioPG82090.41
Frank NtilikinaPG52220.4
Brandon IngramSF78320.39
Bojan BogdanovicSF101330.38
John CollinsPF74530.37
Marvin WilliamsPF84550.37
Noah VonlehPF52660.37
Miles PlumleeC22490.36
Dennis SchroderPG89730.36
Tony ParkerPG41790.36
T.J. WarrenSF72660.33
Jayson TatumSF96930.33
Allen CrabbeSG67560.33
PJ TuckerPF101850.30
D'Angelo RussellPG76610.29
Kyle KuzmaPF99070.27
Zaza PachuliaC37810.26
Davis BertansPF55230.26
Russell WestbrookPG113350.26
Maxi KleberPF54600.26
D.J. AugustinPG79680.25
Robert CovingtonSF75890.25
Willie Cauley-SteinC87910.25
Justin HolidaySG99100.25
Bradley BealSG121510.25
Tobias HarrisPF113450.25
Nikola JokicC98060.25
Kyrie IrvingPG81790.22
T.J. LeafPF20040.21
Langston GallowaySG51780.17
Juancho HernangomezPF32180.17
Jerami GrantPF87860.16
Jose CalderonPG30940.15
Trey BurkePG38850.15
Dion WaitersSG40470.15
Dwyane WadeSG70260.15
Mason PlumleeC63510.13
CJ McCollumSG106630.13
Damian LillardPG111350.12
Jabari ParkerPF50330.12
Larry Nance Jr.C64380.10
Dillon BrooksSF51860.09
Kevon LooneyC50020.08
Ryan ArcidiaconoPG45710.08
Terrance FergusonSG55520.07
JJ RedickSG93580.05
Rajon RondoPG64920.04
Luka DoncicSG47720.04
Courtney LeeSG54790.04
DeMarcus CousinsC51820.03
Nemanja BjelicaPF66470.02
Jahlil OkaforC26960.00
DeMarre CarrollPF7847-0.04
Andre DrummondC10453-0.04
Nick YoungSG2939-0.05
Jamal MurrayPG9955-0.06
Dirk NowitzkiPF5400-0.07
J.J. BareaPG4723-0.08
Doug McDermottSF6224-0.09
Stephen CurryPG8364-0.09
Spencer DinwiddiePG8566-0.10
Cameron PaynePG2649-0.10
Rudy GayPF6105-0.11
E'Twaun MooreSG8498-0.12
Dennis Smith Jr.PG7156-0.14
Ryan AndersonPF4153-0.14
Tim Hardaway Jr.SG8001-0.14
Otto Porter Jr.SF8298-0.18
Kentavious Caldwell-PopeSG9317-0.20
Royce O'NealeSF5707-0.21
Nene HilarioC2750-0.21
Pat ConnaughtonSG5643-0.22
Carmelo AnthonyPF5537-0.22
Jordan ClarksonSG8242-0.23
Matthew DellavedovaPG3003-0.23
Mike MuscalaPF4943-0.23
Tyler JohnsonPG7170-0.24
Shabazz NapierPG5017-0.25
Bryn ForbesSG7653-0.26
Tyler UlisPG3392-0.26
De'Aaron FoxPG9551-0.27
Trey LylesPF5004-0.27
Wilson ChandlerPF7139-0.28
Dwight PowellC6736-0.28
Elfrid PaytonPG6437-0.30
Evan FournierSG8848-0.30
Nicolas BatumSF8896-0.30
Luke KennardSG5646-0.30
Torrey CraigSF4231-0.31
Serge IbakaC8450-0.31
Kris DunnPG5915-0.33
Khris MiddletonSF10978-0.33
James Ennis IIISF5694-0.34
Chandler ParsonsSF2365-0.35
C.J. MilesSF4469-0.35
DeMar DeRozanSG10901-0.36
Jared DudleyPF3905-0.36
Reggie BullockSG7361-0.37
Austin RiversSG8264-0.38
Kevin DurantSF10471-0.39
Evan TurnerPG7315-0.39
Damyean DotsonSG5042-0.39
Markieff MorrisPF6589-0.40
Will BartonSG7674-0.41
Wesley JohnsonSF4220-0.41
Sam DekkerPF3401-0.42
Dario SaricPF8910-0.43
Jalen BrunsonPG3239-0.44
Kenrich WilliamsSF2344-0.44
Maurice HarklessSF5410-0.45
Karl-Anthony TownsC11033-0.45
Jaren Jackson Jr.PF2973-0.45
Isaiah CanaanPG2123-0.46
Tony SnellSF6832-0.47
Ante ZizicC2609-0.49
Mikal BridgesSF5057-0.52
Jerryd BaylessPG3199-0.52
Darius MillerSF7780-0.53
Frank MasonPG2831-0.53
Taj GibsonPF8937-0.54
Jerian GrantPG5220-0.55
JaMychal GreenPF5812-0.56
Solomon HillSF2295-0.56
Jeremy LambSG8519-0.57
Nerlens NoelC3164-0.58
Jarrett AllenC7273-0.58
Jae CrowderSF8643-0.59
Tyus JonesPG6132-0.60
Allonzo TrierSG2917-0.61
Kenneth FariedC2458-0.63
Jonathon SimmonsSG6238-0.65
Wesley MatthewsSF8529-0.68
Jonas JerebkoPF4759-0.69
Trevor ArizaSF9393-0.69
Nikola MiroticPF5836-0.72
Abdel NaderSF2514-0.74
Ed DavisC5897-0.74
Marcus MorrisPF7146-0.75
Wayne EllingtonSG6510-0.76
Patty MillsPG8046-0.76
Rodney HoodSG6972-0.76
Joe HarrisSG8757-0.77
Kyle O'QuinnC3478-0.78
Yogi FerrellPG6762-0.78
Garrett TempleSG7257-0.81
Andrew HarrisonPG2904-0.81
Corey BrewerSF3543-0.81
Kelly Oubre Jr.SF8596-0.82
Ian MahinmiC3316-0.83
Patrick BeverleyPG5098-0.86
Wendell Carter Jr.C2229-0.86
Emmanuel MudiayPG5773-0.87
Marco BelinelliSG7630-0.92
Lou WilliamsSG9584-0.92
Willy HernangomezC2728-0.93
Tyrone WallacePG3183-0.93
Mike ScottPF5815-0.95
Lance StephensonSG6087-0.96
Kent BazemoreSG7093-0.97
Deyonta DavisC2168-0.98
Jakob PoeltlC5628-1.00
Shelvin MackPG5168-1.00
Taurean PrinceSF8310-1.01
Reggie JacksonPG6898-1.02
Julius RandlePF9218-1.03
Bogdan BogdanovicSG8416-1.06
Thon MakerC4401-1.06
Dragan BenderPF6067-1.08
Malik BeasleySG4981-1.09
Deandre AytonC4548-1.10
Cristiano FelicioC3494-1.11
Patrick McCawSG2789-1.11
Mario HezonjaSF5792-1.12
Justin JacksonSF6411-1.13
Gerald GreenSG4874-1.15
Sterling BrownSG3758-1.16
Michael Carter-WilliamsPG2453-1.16
Jordan BellC3293-1.17
Marvin Bagley IIIPF3351-1.17
Amir JohnsonC3582-1.18
Landry ShametSG3785-1.23
Miles BridgesSF3491-1.23
Zach LaVineSG5717-1.24
DeAndre' BembrySG5076-1.24
Zach CollinsC4745-1.24
Enes KanterC6915-1.25
Kevin LovePF4548-1.27
David NwabaSG5281-1.30
Lauri MarkkanenPF7502-1.34
Terrence RossSG5535-1.36
Greg MonroeC3077-1.42
Devin BookerSG8574-1.43
J.R. SmithSG5001-1.43
Quincy AcyPF2941-1.44
Nik StauskasSG3143-1.45
Montrezl HarrellC7310-1.47
Jamal CrawfordSG5819-1.47
Quinn CookPG3598-1.51
Ian ClarkSG5079-1.55
Wayne SeldenSG4322-1.58
Danuel House Jr.SF2841-1.61
Cedi OsmanSF6244-1.63
Kelly OlynykPF7104-1.66
Mitchell RobinsonC2801-1.68
Kevin KnoxPF4428-1.68
Salah MejriC2245-1.69
Gorgui DiengC4865-1.69
Cheick DialloPF3137-1.71
Caris LeVertSF5934-1.80
Tristan ThompsonC4536-1.88
Alec BurksSG4890-1.90
Alex LenC6282-1.91
Iman ShumpertSG3695-1.92
Kyle KorverSG5941-1.94
John HensonC4260-1.96
Trae YoungPG5383-2.03
Channing FryeC2090-2.04
Tyler DorseySG3425-2.04
Dante CunninghamPF5148-2.05
Bismack BiyomboC4574-2.07
Kevin HuerterSG4390-2.09
Bobby PortisPF5973-2.09
Josh JacksonSG8240-2.15
Jarell MartinPF3927-2.16
Alex AbrinesSG3465-2.23
Timothe Luwawu-CabarrotSF3054-2.28
Jeremy LinPG3140-2.32
Devin HarrisPG4853-2.33
Milos TeodosicPG2651-2.34
Vince CarterSF4856-2.37
Troy DanielsSG4890-2.38
Daniel TheisC3688-2.42
Collin SextonPG5179-2.42
Frank KaminskyC5248-2.53
Skal LabissierePF2854-2.55
Michael BeasleyPF3813-2.57
Justin AndersonSF2074-2.62
Meyers LeonardC2290-2.67
Tim FrazierPG4012-2.90
Ben McLemoreSG2506-3.09
Jodie MeeksSG2425-3.16
Marquese ChrissPF4187-3.17
De'Anthony MeltonPG2036-3.27
Ivan RabbPF2494-3.39
Malik MonkSG4347-3.55
Antonio BlakeneySG2317-4.15

The first thing that pops out is Rudy Gobert at the top of the list by a significant margin. Considering Gobert has won the Defensive Player of the Year award both of the seasons which this data covers, it isn’t surprising to see him at the top. Aron Baynes may be higher than he would be if he had played as many possessions as some of his fellow players, but he is certainly known as an extremely good defensive big man. Finally, Jrue Holiday rounds out the top three with the highest DVAL of any non-center. This isn’t surprising either. Holiday has deservedly been named to an All-Defensive team each of the past two years and he is routinely matched up against the opposing team’s best wing players. Among the players he defended most often over the past two seasons were James Harden, Kevin Durant, Paul George, Damian Lillard, Donovan Mitchell, and Jimmy Butler. Not bad.

At the bottom of the table, there are also not many shocking results. The defensive struggles of Antonio Blakeney, Malik Monk, Marquese Chriss, and Collin Sexton are not well-kept secrets. Meyers Leonard’s ranking as the worst defensive center in the NBA probably isn’t a surprise to any fans of the Portland Trail Blazers.

Jahlil Okafor’s two-year DVAL is basically exactly zero due to a below-average 2018 season followed by an above-average 2019 season with the Pelicans. Some of the league’s elite scoring point guards (Stephen Curry, Kyrie Irving, Damian Lillard, and Russell Westbrook) are also hovering around average ratings, which make sense. None of them are game-changers on defense, but they also aren’t liabilities like they are sometimes portrayed to be.

Speaking of elite offensive players who are described as below-average defenders, James Harden comes in as the 8th best defensive point guard on the list with a DVAL of 1.34. Considering how often people say he “doesn’t play defense,” you’d expect something lower. Instead, this metric backs up the claim that Harden’s defense has become underrated.

Another polarizing player on the defensive side of the ball is LeBron James. A glance at LeBron’s defensive FG% numbers would lead you to believe that he has become heavily underrated in that aspect of the game. However, those numbers may be inflated because of the players he tends to guard. The six players LeBron was matched up with for the most possessions last season were Bojan Bogdanovic, DeMarre Carroll, Dario Saric, Michael Kidd-Gilchrist, and Stanley Johnson. DVAL takes this into consideration and gives him a more accurate evaluation as the 13th best defensive small forward in the league. Well, in the regular season, at least. We can’t count out playoff LeBron.

Although many of these results match the eye-test, some of them do not. Is JJ Redick actually a slightly above average defensive player? Is Darren Collison really as good of an individual defender as Draymond Green? And is Joel Embiid legitimately a worse defender than guards like Kemba Walker and TJ McConnell? To be clear, excessive use of the eye-test to judge new metrics isn’t a good idea because the unreliability of the eye-test is the exact reason we need metrics. However, some discrepancies deserve to be pointed out.

So, what’s the problem? Why is individual matchup data sometimes giving us results that don’t make sense? Let’s imagine the following scenario: a defender allows his matchup to blow by him, forcing another defender to provide help and pick him up, which leaves another offensive player open for a three-pointer. Well, the initial defender deserves blame for allowing his matchup to blow by him for what would have been an easy bucket if not for the help defense. So, the NBA’s matchup data notes that the offensive player was credited for an assist during the matchup. However, what if that player gets an assist when it isn’t the defender’s fault? What if the defender’s teammates are playing bad off-ball defense while the primary defender is playing good on-ball defense? In both situations, the result is the same: the offensive player assists a teammate for a bucket. However, the blame on defense switches completely. It’s not easy to capture this with basic matchup data because there’s far too much nuance in basketball.

In conclusion, DVAL is like any other defensive metric in the sense that it’s nowhere near an extremely reliable all-in-one stat, but it also doesn’t appear to be entirely useless. Maybe with future improvements in player tracking systems, more reliable metrics can be used to tackle the problem of defensive evaluation in the NBA.

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