Secrets of an NBA Defense

Fred Katz@@FredKatzFeatured ColumnistJuly 31, 2014

Los Angeles Clippers guard Jamal Crawford, left, puts up a shot as Golden State Warriors forward Andre Iguodala defends during the second half in Game 5 of an opening-round NBA basketball playoff series, Tuesday, April 29, 2014, in Los Angeles. The Clippers won 113-103. (AP Photo)
Uncredited/Associated Press

Don't you even watch the games?! 

You can quote the individual stats all you want, but at some point, when you're talking about defense, you're going to hear someone condescend to you with that phrase if you don't move on from the numbers. 

Looking at team stats seems to be more logical when you evaluate defense, mainly because defending is a team action, not necessarily an individual one.

Cite team points allowed per possession (defensive efficiency) instead of team points per game, and you're heading in the right direction. At least you'll be accounting for game pace. But still, you can't just throw out individual defensive numbers and consider them gospel, especially the mainstream ones.

Andre Iguodala's 1.5 steals and 0.3 blocks per game hardly begin to explain how dominant of a stopper he is on the perimeter. Tyson Chandler's 1.4 blocks a night don't show how many attempts he altered during his Defensive Player of the Year campaign a couple seasons ago.

Statistics tend to tell exactly what happens with the ball. Was it scored? Was it stolen? Passed? Rebounded? Blocked? But proper defense isn't necessarily around the ball. It's about what you do when you're away from it.

Beyond the Numbers

Mark J. Terrill/Associated Press

NBA defense is more about five men guarding the ball as opposed to five players guarding their individual assignments. Off-ball defense is the most important part of defending in the pros.

That's why you see Defensive Player of the Year almost guaranteed to a big man every season. Since 1989, only two non-bigs (Metta World Peace—or Ron Artest at the time—and Gary Payton) have won that award. Bigs make far more of an impact off the ball than guards and wings. That's why we commonly call them the "anchors" of the defense.

Big men like Joakim Noah, Marc Gasol and Serge Ibaka have all learned how to play help defense effectively. 

Blocks tend to come from help defenders flying over from the weak side, throwing a hand at the ball as a shot goes up somewhere around the hoop. How often are we really seeing a defender block his own assignment? Not very much.

On-ball defense is clearly an essential aspect of the game, and having lockdown defenders can make your team attack so much more relevant, but adjusting shots from off the ball is a skill not many players possess.

Protecting the Rim

SALT LAKE CITY - 1989:  Mark Eaton #53 of the Utah Jazz stands next to Kareem Abdul-Jabbar #33 of the Los Angeles Lakers during an NBA game at The Salt Palace in Salt Lake City, Utah in 1989. (Photo by Mike Powell/Getty Images)
Mike Powell/Getty Images

Cliff Levingston, a power forward who played for the Detroit Pistons, Atlanta Hawks and Chicago Bulls in the '80s and into the '90s probably said it best when talking about former Defensive Player of the Year and 7'4" behemoth Mark Eaton, who would alter shots like no other:

"He changes your shots when he's in the game. He also changes your shots when he's out of the game because you get so used to trying to throw it over him, you forget when he's not there."

Notice the term Levingston chooses: "changes your shots." He's not talking about blocking attempts, just altering them.

That's the mistake so many people make when they look at a rim-protector. The first thing they check is blocked shots, but that stat doesn't always tell the story of a true rim-protector. 

Even if a player averages two or three blocks per game, that still leaves 60-plus possessions a night unaccounted for if he's a guy who plays a decent amount of minutes. And often, you'll find guys who get block happy.

That's why JaVale McGee isn't considered a premier defender even with his flashy block numbers. He flies after every shot opportunity, often finding himself out of place. Not only is he not altering shots because of that, but he's also forcing another defender to come help and taking himself away from the rim, removing a potential rebounder on a shot attempt.

That's what Ibaka used to do. It's what DeAndre Jordan still does at times but has cut down on immensely. Once those guys changed, their defenses did with them.

Defense is merely about rotating to the right spot and knowing where to be. It's about understanding and executing scouting reports. Heck, that's really what makes someone like Draymond Green such a brilliant help defender.

Get off the Ball

LOS ANGELES, CA - MAY 03:   Blake Griffin #32 of the Los Angeles Clippers drives against Draymond Green 323 of the Golden State Warriors in Game Seven of the Western Conference Quarterfinals during the 2014 NBA Playoffs at Staples Center on May 3, 2014 in
Stephen Dunn/Getty Images

Guarding off the ball is essential because it affects where 80 percent of the offense can be on the floor. If a defense is taking away a ball-handler's options, it can force the offense into bad decisions and poor shot selection, and that's ultimately the goal of defending.

Part of that goal includes taking away an offensive player's ability to get optimal positioning on the floor.

Knowing that, the way we tend to judge post-up offense is generally incorrect. If a player doesn't have many "pretty moves" in the post, if he lacks an arsenal that includes an aesthetically pleasing up-and-under, a couple baby hook shots and a spin move or two, we say a guy can't play down by the basket. But moves can be secondarily important to becoming a strong post-up player.

Scoring in the post is all about positioning before you receive the entry pass, and defending it is about that fight to push your man further from the hoop.

Strong post defenders, like Draymond Green, will reposition players all the way out of the paint, placing ball-handlers in that uncomfortable nine-to-13-foot range away from the rim. Look at how far out Green gets Blake Griffin, one of the NBA's best before-receiving-the-ball post-up players, on this postseason play.

Here's where Griffin makes his first move to back Green down:

Synergy Sports

This is where he eventually fields the entry pass from Chris Paul:

Synergy Sports

Green didn't just hold his ground. He pushed Griffin even further from scoring territory, and the Clippers forward eventually missed his shot.

Conversely, let's look at another play, this one from Ryan Hollins as he guards Timofey Mozgov. See how deep in the paint the Russian stands?

Synergy Sports

Mozgov scored on an easy right-handed hook shot on his play. Griffin clanked his righty hook. Those plays are all about positioning, and Green and Hollins' off-ball efforts ultimately swung the possessions for their teams.

If a strong NBA post player gets the rock with a foot already in the paint, he has a good chance to score. If an he receives a pass with two feet comfortably around the restricted area, you're almost definitely going to see a good look.

The Analytics Era

As the analytics era moves forward, we are finding more and more numerical ways to quantify defense. There's Synergy Sports and SportVU, both of which provide tremendous and gluttonous data far beyond what people within NBA circles ever could've imagined. 

Most of the information those two basketball statistical databases provide remains private, exclusive to the teams, themselves (that's more true for SportVU). But we still see plenty of public information. And when scrolling through the Synergy database, we have to remember defensive statistics, like any, are all about context. 

So often, you'll see someone throw a number out there—Player X allows Y points per play when guarding against pick-and-roll ball-handlers. But while those numbers can be tremendously helpful, they don't provide all that much information below the surface. 

That statistic doesn't take into account how Player X's team defends the screen-and-roll. Do they ice it, driving the dribbler to the out-of-bounds line? Do they zone it up, letting their bigs sag back and giving up potential mid-range shots? Do they switch, and if they do, are they communicating well?

It doesn't acknowledge the other four defenders on the floor. Who's guarding the screener? How much help is there? Is there anyone in the paint clogging up the lane?

It doesn't tell what happens when a defense stymies the pick-and-roll, forcing the offense to reset and go to another play. 

In reality, it doesn't tell that much. 

A New Kind of Defense

For all those reasons, we're still struggling to quantify defense numerically, only leading to all of those "Don't you watch the games?!?!" critiques. 

Still, SportVU has made some incomprehensible strides in recent years. Just look at the "ghost defenders" piece that Grantland's Zach Lowe wrote in March of 2013.

As detailed in the article (which is still perfectly relevant), SportVU will track exactly where both the offensive and defensive players ventured on the court. It then adds to the video the optimal positions in which the defenders should move, the "ghost defenders." As Lowe said, "The future of the NBA looks like this":

Lowe continued:

That’s Jason Kidd hitting a 3-pointer off a Carmelo Anthony pick-and-roll in the first quarter of Toronto’s February 22 home win over the Knicks; the Knicks are in blue, passing the little yellow ball around, and the Toronto players are colored white. It looks simple, but the process of getting there took a bunch of people, including three Toronto front-office employees, more than a half-decade of work. In simple terms:

The Raptors’ analytics team wrote insanely complex code that turned all those X-Y coordinates from every second of every recorded game into playable video files. The code can recognize everything — when a pick-and-roll occurred, where it occurred, whether the pick actually hit a defender, and the position of all 10 players on the floor as the play unfolded. The team also factored in the individual skill set of every NBA player, so the program understands that Chris Paul is much more dangerous from midrange than Rajon Rondo, and that Roy Hibbert is taller than Al Horford.

That is truly a breakthrough for evaluating defense, something that actually allows for team concepts within a scheme. Because that's all defense is, right? A series of team concepts.

If you can identify when guys are moving to the right spots defensively, that's a start, but we're still inching toward a way to quantify those actions properly, at least for individuals. And until we do, we're just going to have to watch the games.

Fred Katz averaged almost one point per game in fifth grade, but he maintains that his per-36-minute numbers were astonishing. Find more of his work at, or on ESPN's TrueHoop Network at Follow him on Twitter at @FredKatz.

Unless otherwise noted, all statistics are current as of July 30 and courtesy of and


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