A Different Perspective: Defensive Scoresheets

Dateline: 01/06/00

IN THE MID-1990'S, NBA DEFENSES finally caught up to the offense. Floor percentages dropped to 50% and offensive ratings fell to just above 100. After the go-go '80's when offensive giants like Magic Johnson and Larry Bird dominated the league, the defensive-minded Pistons rang in the '90's with titles built around brutality. The Bulls won throughout the '90's with both the best offensive threat in the league and multiple outstanding defensive players. Other top teams in the late '90's, such as the Knicks, Sonics, Spurs, Heat, and Jazz consistently had solid defenses. Rotating defenses to the open man became as prevalent as offenses rotating to the open man. Defenses also looked better because so many young players came into the league unable to hit the midrange jumper, but there's no reason to be cynical here...

This article is going to introduce a new tool for examining the game: Defensive scoresheets. The point of a defensive scoresheet is to look at the game from a different perspective. Forming that different perspective, however, is extremely difficult. Developing the method for scoring the defense is just one step in a shift of mindset where the person scoring the game doesn't look so much at who made a basket, but at who was around to potentially stop the basket. Who made an assist isn't as important as identifying who should have helped out defensively.

This change of perspective is not an instantaneous accomplishment. I've been working on it for, in effect, many years. I know what is important defensively (coaching defense was my specialty), but it was always difficult to quantify what it was that players were doing to be good defensive players. I have always looked at the defense when watching a game, but that is different from tracking what precisely it does.

Described below is a method for tracking what a defense does. I won't say that it's perfect, but it has changed the way I look at the game to some degree. And that is important.

...Introduction to the System...

The Defensive Possession Scoring System (DPSS) looks a lot like the original PSS, which tracked the players who touched the ball and what they did with it. The DPSS tracks the players covering the ball, which sounds easier than it is. It often happens that it isn't clear who is covering the ball. There are times when no one is covering the ball and there are times when multiple players are covering the ball. Further, in most leagues, teams play zone defenses, which makes assignments even more vague.

The example game we'll use to introduce the method is Game 5 of the 1999 NBA Finals, with two solid defensive teams - the San Antonio Spurs and the New York Knicks - facing off in Madison Square Garden with the Spurs leading 3-1 in the series. This scoresheet will tell a very different tale than you are used to.

...The Game In Scoresheet...

Welcome to the fourth quarter of an intense defensive matchup. Entering the quarter, it's 59-58 San Antonio.

59 NYK   20D_14 14 20_14-2 20R

In this, the first possession of the fourth quarter, New York is playing defense, which is why "NYK" is indicated on the line. Allen Houston picks up the dribbler (20D), then gets help from Chris Dudley, the help indicated by the underline linking Houston's number 20 to Dudley's number 14. Dudley picks up the coverage on his own, then Houston again. Houston gets help from Dudley to force the miss in the middle of the key (20_14-2). Houston snares the rebound to shut down San Antonio's attempt at a score (20R).

As with the offensive PSS, shots are indicated with either a dash (-) indicating a miss, a plus (+) indicating a made shot, or a double-plus (++) indicating a made shot and an assist. The subscript on the shot indicator signifies the location from which the shot is taken according to the following figure:

shot chart locations symbols
58 SAN   31_21-L 31R

San Antonio's team -- a group anchored by two of the best defensive players in the league, Tim Duncan and David Robinson -- starts the fourth quarter with Malik Rose, number 31, picking up the first defense. He gets help covering the layup from Duncan (31_21-L), Rose getting the missed shot and sending New York to the defense.

At this point, we raise the question of how to distribute the credit for the team's defensive stop. Here, Rose and Duncan combined to force a miss, which is half of the equation. Duncan picked up the defensive rebound, which is the other half. On the surface, let's assign Duncan 2/3 of the defensive stop and Rose 1/3 of the stop.

Using the same rationale, the Knicks' first stop above is distributed as 2/3 to Houston and 1/3 to Dudley.

61 NYK   1 8 14D_8+1

New York's Chris Childs (1) picks up the defense in the halfcourt. Sprewell (8) takes over when his man gets the ball. Dudley's man puts the ball on the floor to go around him, drawing the help from Sprewell, but they can't stop the jumper from the flank (14D_8+1). The Knicks fall another two points behind, 61-58.

60 SAN   33D 32F32 33 21++R

Trying to build on their lead with a stop, the Spurs' Antonio Daniels picks up the dribble (33D) before Sean Elliott picks up his man and commits a foul (32F32). After Daniels picks up the inbounds, Duncan allows the assist to his man under the basket (33 21++R). The Knicks get back to within 1 at 61-60.

In neither of the last two possessions did the defense stop the offense. Hence, no defensive stops can be credited to individuals.

61 NYK   1D_8 8D_14_2STL

Childs picks up the dribbler, Sprewell giving help. Then Sprewell takes the defensive responsibility himself, getting help from Dudley and finally Larry Johnson picks up the steal (8D_14_2STL).

Here, one can distribute the stop here among Sprewell, Dudley, and Johnson.

63 SAN   33 31D+A F31*

Often after a turnover, a team gets an easy shot at a hoop. In this case, it looks like Daniels gets back and Rose gets caught trying to defend the jumper, also committing the foul, giving up the three-point play and giving the Knicks the lead at 63-61.

63 NYK   8 20 14D+3

Holding the lead, the Knicks need a stop to keep it, but can't here, with Dudley unable to defend the post (the post-up denoted by the underline).

63 SAN   33 32_31F21 TIME 9:44 6 21_17 6 17D-2 17R

After the Duncan foul and the timeout, the Knicks try to post up on Duncan, Duncan getting help from Mario Elie (17). Avery Johnson picks up the D, then Elie guards his man into the lane, forcing the miss, and getting the board. Credit this entire stop to Elie.

63 NYK   1 2_1 1_14 14-B 8R

Here, Dudley is involved in another stop, forcing the miss from just above the free throw line. Sprewell grabs the defensive rebound, sharing the defensive stop with Dudley.

66 SAN   32D+Y TIME SAN 8:57

In a clear momentum shifting possession, the Knicks hit a three-pointer over Elliott, giving them a 3 point lead and forcing the Spurs to call timeout.

65 NYK   8 1D F14 1D 14D+2

Given that the Spurs big offensive weapons are big guys, Duncan and Robinson, it is no surprise that Dudley gets more action here, picking up a foul and giving up the field goal from the key.

At this point, let's also keep track of the number of possessions a player ends. In this case, by distributing individual defensive possessions evenly among those players sharing in the end of a possession, Dudley now has 3 2/3 defensive possessions and 1 1/3 individual defensive stops.

68 SAN   6 50 6 17 32++3

67 NYK   1D 2 20 14_1_8_1_20D+2
68 SAN   6 17 32_21_50STL
68 NYK   2 20 8 1_14_2_14F14*X 20 1D_23-RROB 2 8D-2 23R

Note the missed foul shot in the middle of the possession. Someone on the offense rebounded that miss to continue the possession. The Knicks didn't close out the possession with the defensive rebound, so they had to face two more field goal attempts before they got the defensive board.

Allowing an offensive rebound is one of the things a coach cannot stand (even though it happens about a third of the time). You always have to look around for who didn't box out, but, in reality, the person who gets an offensive rebound is often free because his defender goes to double-team or because they are in the right place. In the case of an offensive rebound off a missed foul shot, neither of these excuses usually can be used. Someone on the Knicks screwed up here.

71 SAN   6 17D (ILL D T X) 6 17_6 17_32F32 6 2 17_21 50++LF50*

In this last possession, we see an illegal defense technical foul for the first time. Fortunately for the Spurs, the Knicks missed the foul shot (ILL D T X), otherwise this would have been a really bad possession. Already, Elliott and Robinson picked up fouls and the Spurs gave up 3 points here to give New York the 71-68 lead.

68 NYK   1_2_23_1 8 23_1D-2 2R
71 SAN   17 50-A 21R
70 NYK   1 8 23KOB TIME 5:35 20D-A 23F23**
73 SAN   2 17_21_50_32D_50_17++D
72 NYK   20 23++LF23X 2R
73 SAN   6 TIME NY 4:49 21 6 17D_21 21-Y 17R
72 NYK   1 23 8-2 2R
75 SAN   6 32D+A
75 NYK   1 23 2_23 23++Y

At this point, with the Knicks giving up the open three pointer here, the game is tied at 75 with three minutes to go.

77 SAN   6 17 21 32D 21F21**

San Antonio gives first, on the foul from Duncan. Sprewell makes the two foul shots, but the Knicks would not score again.

76 NYK   1 23 20D_1 20-X 8 20_23_8_1 2F2X*

The Spurs attack and, after a rebounded miss three point attempt, force the Knicks to scramble (very common after an offensive rebound), eventually drawing the foul on Johnson. Duncan hits the second of two free throws, drawing the Spurs to within 1.

77 SAN   6 50 21 32D-LBK21 JUMP 50,23 6 TIME NY 2:05 32D_21 32 21_32 24-S CK TO

One of the benefits of a blocked shot that some people forget about is that it can more easily cause a 24-second clock violation, which is what Duncan's block helps to cause here.

76 NYK   1 8 20 2_8_20_1_8_23-2 8R

Massive rotation defense here by the Knicks forces the miss and the defensive rebound, maintaining the Knicks' one point lead.

77 SAN   6 32 6 32 6_21 50-Y 17R

The Spurs get another stop that they absolutely need. Here, the Knicks were going for the knockout punch with the three-pointer, but Robinson flashed out to get in the shooter's face, forcing the miss.

78 NYK   1 2_8 1 TM++A TIME NY 0:47

The Knicks play halfcourt defense with Childs at the point. LJ is forced to play defense in the post with Sprewell coming over to help. The rotation back to Childs' man, then over to Sprewell's man (Elie) who was still open -- making you wonder whether the defensive rotation failed or whether Sprewell got lazy. Here, we call it team defense that allowed the open assisted hoop from 17 ft. The Knicks call timeout with 47 seconds left to regroup.

77 SAN   6 32D-C 6R

New York runs Sprewell at Elliott, who handles the dribble drive and forces the missed 14 footer off the right wing. Little man Avery Johnson collects the defensive board.

78 NYK   1 23D-R 23 8 1-Y 2R TIME NY 0:02.1

The Spurs run the clock down as much as possible before the hasty miss of a three pointer by Johnson. With the rebound of the miss, the Knicks call timeout with 2 seconds to play.

77 SAN   32_21_50-L

Perhaps you remember Sprewell driving the left baseline. The Spurs knew he was going to shoot it and they sent their big guys to help Elliott on the defense. It wasn't clear whether Sprewell actually got a shot off, but the Sportsline scoresheet said he did. Regardless, it didn't go in the Spurs defense saved their championship.

...Some Final Numbers...

Over the course of the game, one can distribute the individual defensive stops and individual defensive possessions as mentioned here. If you do, you see the following breakdown at the end of the game:

San Antonio
# Player Stops Poss Stops/Poss
32 Sean Elliott 4.2 13.2 0.316
21 Tim Duncan 11.3 18.7 0.603
50 David Robinson 6.4 10.6 0.606
17 Mario Elie 7.0 10.8 0.646
6 Avery Johnson 3.3 4.8 0.690
31 Malik Rose 1.5 4.9 0.306
4 Steve Kerr 0.5 0.5 1.000
2 Jaren Jackson 6.2 7.7 0.801
33 Antonio Daniels 1.3 1.5 0.889
  Team 2.3 8.3 0.280
    44 81.0 0.543
New York
# Player Stops Poss Stops/Poss
2 Larry Johnson 6.0 9.6 0.626
8 Latrell Sprewell 9.7 14.8 0.651
23 Marcus Camby 6.8 12.0 0.571
20 Allan Houston 4.2 5.8 0.723
21 Charlie Ward 4.2 8.1 0.512
1 Chris Childs 0.8 1.2 0.676
14 Chris Dudley 4.2 9.1 0.457
40 Kurt Thomas 5.2 12.3 0.419
32 Herb Williams 0.0 0.0 ----
  Team 3.0 8.0 0.375
    44 81.0 0.543

This is about as even as it gets...

I tend to think that there is another shift in perspective that needs to occur in order to really generate a useful defensive scoresheet. That shift is not to watch the ball. A good defense only has peripheral vision of the ball. Bobby Knight has stated that watching the defense off the ball is one of the most important things for a coach to do. But how does one translate this into a scoresheet that tells a clear story? I'm still working on this. In the meantime, this method holds some promise.