From the Vault: Observations from a season of Stat-Tracking

This post was originally published on April 13, 2011. It is a summary of findings after one year of stat-tracking basketball games in attempt to extend the box score. SportsVU now captures similar data. 

If one spends enough time watching NBA games with a DVR, trends start to jump out. Unfortunately, there’s no way the human brain can accurately catalog all that information. Perhaps Data from Star Trek should be assigned to finding trends in basketball games. In the meantime, here are some statistical observations from roughly 23,000 possessions of stat-tracking in 2011:

Creation

  • 16% of all field goals came off of an Opportunity Created (OC).
  • 46% of 3-pointers came off of an OC.
  • The average player shot 40% on 3-point shots off of an OC.
  • The Spurs led the league in OC’s (23.5 per 100 possessions), with the Hawks second at 23.4.
  • The Jazz needed the most help on defense — which means their opponents create the most opportunities (23.7 OC per 100).
    • The Jazz had the lowest Defensive Rating in the sample by far (118.7).

Fouling

  • The Lakers committed the fewest shooting fouls in the league (16.5 free throws/100).
  • Someone takes an offensive foul every 88 possessions…or a little more than once per game.
  • Phoenix takes more offensive fouls than any other team – 2.2 per 100 possessions.

Defense

  • In guarded situations, the most successful teams are the best defensive teams: The four leaders in guarded field goal percentage are in the top-5 in defensive rating (and Milwaukee’s sample was too small):
    1. Miami (36.6%)
    2. Chicago (36.6%)
    3. Boston (36.9%)
    4. LA Lakers (37.7%)
  • The Lakers make the most defensive errors…but give up the fewest points per error (1.50 points/error), a credit to Andrew Bynum and Pau Gasol protecting the paint.
  • Every 172 possessions there is a forced turnover not counted as a steal (eg slapped off a leg out of bounds. That means the NBA doesn’t track about 1700 “steals” during the season.
  • Teams shoot the worst in unguarded situations against the Lakers (56.6% eFG%), which suggests that LA does well closing out shots and fighting through screens…or they’re just lucky.

Top “Healthy” Teams in NBA History

Who are the best teams in NBA history? We often answer this question by looking at a team’s entire body of work, lumping in the good, the bad and the injured. Most teams have key players miss games and some even trade for key players, changing the chemistry of a given lineup. So who were the best teams when all of the key actors were on stage?

Below I’ve indexed the top “healthy” teams — when all 25-minute per game players were in action for a game — since the shot clock (1955) by SRS (adjusted margin of victory). Using this criteria, 51 teams have posted at least an 8.0 SRS when healthy.  Just 29 teams have eclipsed the 9.0 mark. (10 of those teams failed to win a title — well inline with what is predicted by the variability of a 7-game series.) The best are below, playoffs included:

Top Healthy Offenses

Disclaimers: SRS, while a better predictor of results than win percentage, is not a de facto team-ranker. First, it’s subject to the usual variance seen in the NBA (detailed in Chapter 4 of Thinking Basketball), so it’s not a perfect representation of team strength. Second, some teams are more resilient in makeup — they are better equipped at handling a variety of opponents while still remaining efficient, boosting their odds of winning from series to series. Finally, SRS is a measure of within-season dominance, so it cannot allow for perfect comparisons across seasons. A 10 SRS in 1986 is probably more impressive than one in 1972.

With that said, it is by far the single best metric for evaluating the performance of a team against its competition. The teams listed above were manhandling opponents, which is why many went on to win a title.

While this year’s Warriors were the most dominant single-season team ever, their SRS is influenced by a league that was incredibly top-heavy. Four of the top-40 healthy teams ever played in 2016 (Golden State, San Antonio, Oklahoma City and Cleveland), which is either an unlikely coincidence, or a reflection of inflated numbers from a lopsided league.

The other top four seasons are from expansion eras, when teams could pick up an additional point or two by facing expansion squads a few times a year and padding their numbers with blowouts. All of those teams are in the conversation for “greatest ever,” but their statistical dominance here should be slightly curved.

As mentioned, we see the usual suspects: Jordan’s first three-peat Bulls. Jordan’s second three-peat Bulls. Kareem’s Bucks and the early 70’s Lakers. This is all line with in-depth analysis of the greatest teams ever.

So who are the most impressive teams of all-time that you probably didn’t know about:

  1. 2014 Spurs. When healthy, they posted an amazing 11.8 SRS. That team is basketball’s Sistine Chapel and Gregg Popovich its Michelangelo.
  2. 2004 Pistons. Absolutely impregnable after the Rasheed Wallace trade in ways that reminded everyone it was time for a rule change.
  3. 2008-09 Lakers and Celtics. These teams were fantastic in an incredibly competitive league. The Celtics were +8.8 and +9.3 when healthy, and the Lakers +9.7 and +9.0 once Pau Gasol joined. Kevin Garnett’s injury robbed us of possibly the NBA’s greatest trilogy.
  4. 1996 Magic. Yes, they were worthy of a documentary.

Amazingly, of the top 40 healthy teams of all-time, seven are Pop’s Spurs teams. Five are Jordan’s Bulls. Four are Laker teams with Kobe Bryant.

Remember this list the next time you construct an all-time list or you look ahead to the 2016 season.

Edit: This post was updated to include the postseason totals for the 2016 Warriors, and 96-97 Bulls. 

From the Vault: Exploring the Spacing Effect

This post was originally published on November 26, 2011. It examines a concept mentioned in my new book, Thinking Basketball

One of the more dominant themes of this summer’s Online Hoops Summit of Nerdness was the “Spacing Effect” that good shooters provide for an offense. By being a threat to score from all over the floor, shooters pull out defenders who could otherwise help on penetration or flood the paint for defense and rebounding. For example, in the last post we combed over five years of raw on/off data — how well a team performed with a player in the lineup versus when he was on the bench — and some of the biggest impacts were made by great shooters.

Of the 21 players who added at least six points of efficiency to a 107 offense (teams averaging 107 points or more per 100 possessions without the player), seven are on the all-time top-100 list of 3-point percentage leaders (minimum 500 attempts). 17 of the 21 (81%) used the 3-point shot regularly, with only Brad Miller (2004), Shaquille O’Neal (2005), Kevin Garnett (2008) and Tyson Chandler (2008) operating primarily inside the arc. The average 3-point percentage from that group was a whopping 38.2%. (League average 35.7% over that time.)

Below are the 21 player seasons, with their 3-point percentage:

Player Year Net Change Ortg On Court Ortg Off Court Season 3 pt %
Josh Howard 2004 6 117.6 111.6 .303
Radmanovic 2008 8.6 119.5 110.9 .406
Williams 2008 6.1 116 109.9 .395
Nowitzki 2004 6.2 115.6 109.4 .341
Bryant 2008 6.5 115.4 108.9 .361
Lewis 2005 7.3 116 108.7 .400
Joe Johnson 2005 8.4 117 108.6 .478
Josh Howard 2007 6.5 114.9 108.4 .385
Allen 2005 7 115.2 108.2 .376
Marion 2007 8.6 116.8 108.2 .317
Radmanovic 2005 11.7 119.8 108.1 .389
Chandler 2008 6.9 114.5 107.6
O’Neal 2005 7.6 114.9 107.3
Christie 2004 6.7 114 107.3 .345
Finley 2005 6.8 114 107.2 .407
Posey 2006 6.2 113.4 107.2 .403
B. Miller 2004 7.5 114.6 107.1
Billups 2008 8 115.1 107.1 .401
Terry 2006 8.5 115.5 107 .411
Garnett 2008 8 115 107

Also from that five-year chunk of data, there were 55 instances of players boasting an on/off of 9.0 or better on offense (minimum 1000 minutes played). Again, this means their teams offense scored at least nine more points per 100 possessions with them on the court that year. Only ten of those seasons saw a player attempt less than one 3-point shot per game. We see the same results: the other 45 (82% of the group) averaged 38.4% from behind the arc.

Of particular interest are the shooting specialists. Who we classify as one-dimensional shooters is somewhat subjective, but it’s a mighty coincidence that Vladimir Radmanovic appears on the above list twice, with two different teams. And that Peja Stojakovic does the same, in two different situations, in his two best 3-point shooting seasons (43.3% in 2004, 44.1% in 2008). And that Damon Jones seemed to help Miami so much in 2005 with a career-best 43.2% from downtown. And that Fred Hoiberg led the league in 3-point percentage in 2005 at a staggering 48.3% and booted Minnesota’s offense while on the court.

Of course, making so many 3′s is also part of the reason these players are helping so much, but perhaps not quite as much as one would think. In Hoiberg’s case, he attempted 4.1 3′s every 36 minutes, which means the difference between 48.3% and league average was roughly 1.6 points per 36 minutes, or about 2.3 points/100 at Minnesota’s 2005 pace. Radmanovic launched 5.7 3′s every 36 minutes in 2008, and if he converted at league average the Lakers would have scored about 1.8 fewer points in his games.

So while greater accuracy translates directly to more points, something else is happening here indirectly. It’s possible these shooters are repeatedly the beneficiary of coming in and out of the lineup with their team’s superstars. Although that seems unlikely, we can look at long-term adjusted plus-minus (APM) data and see the same pattern.

In Joe Ilardi’s 2003-2009 APM model, the best offensive players in the league are names we’d expect: Steve NashLeBron JamesKobe BryantChris Paul and Dwyane Wade. It’s also littered with resident shooters, like Antawn Jamison (“stretch” power forward) at No. 7, Michael Redd (12th), Ray Allen (13th), Jason Terry (19th), Anthony Morrow (21st), Peja Stojakovic (22nd), Rashard Lewis (23rd), Danilo Gallinari (26th), Anthony Parker (40th), Mike Bibby (45th) and Sasha Vujacic (48th). Below are how the top-50 3-pooint shooters (500 attempts) by percentage scored in Ilardi’s APM study:

Player 3P% Off APM
Jason Kapono .454 -1.36
Steve Nash .439 8.84
Anthony Parker .424 2.55
Ben Gordon .415 2.37
Raja Bell .414 -1.22
Daniel Gibson .412 1.40
Bobby Simmons .410 -0.61
Brent Barry .409 0.32
Matt Bonner .409 1.00
Peja Stojakovic .409 4.15
Bruce Bowen .408 -4.99
Wally Szczerbiak .406 1.08
Leandro Barbosa .404 0.51
Kyle Korver .404 -0.20
Eddie House .403 -1.88
Mike Miller .402 1.21
Chauncey Billups .401 5.32
Matt Carroll .400 0.39
Troy Murphy .398 0.41
Roger Mason .395 -0.58
Brian Cook .394 -2.41
Danny Granger .393 1.40
James Jones .393 1.80
Ray Allen .392 5.33
Steve Blake .392 -0.08
Luther Head .392 -1.21
Shane Battier .391 0.33
Rashard Lewis .390 3.91
Michael Finley .389 -1.58
Kevin Martin .389 1.10
Jameer Nelson .389 0.14
Hedo Turkoglu .389 1.89
Jason Terry .387 4.41
Mo Williams .386 1.39
Tyronn Lue .384 -0.47
Jose Calderon .383 0.71
Vladimir Radmanovic .381 1.84
Michael Redd .381 5.46
Kirk Hinrich .380 -0.88
Mike Bibby .379 2.31
Joe Johnson .379 1.40
Dirk Nowitzki .379 4.71
Mike James .378 -0.80
Delonte West .378 -0.39
Andrea Bargnani .377 -1.24
Maurice Evans .377 0.26
Mehmet Okur .377 -0.48
Sasha Vujacic .377 2.24
Manu Ginobili .376 4.94
J.R. Smith .376 1.98
Derek Fisher .375 -1.60

The average Offensive APM in the entire study was -0.45. The average Offensive APM of the top-50 3-point shooters on the list is +1.08. 32 of the 50 were positive-impact players. The glaring outlier, Bruce Bowen, can be explained away quite nicely. We’re using the 3-point shot to approximate outside shooting ability (or the threat of outside shooting), and Bowen isn’t a very good outside shooter. Using available data, he took about one deep jumper a game from 2007-2009 converting at 38%. He shot 57.5% from the free throw line during the period, the worst of anyone of the list by nearly 8%.

We could further define “good outside shooters” by looking at floor data on shooting from 16-23 feet if we wanted to. Although, despite the presence of someone like Bowen, 3-point shooting is sufficient for now to demonstrate the presence of the Spacing Effect.