It's easy to look at the Golden State Warriors and point to their offense as the source of their early season dominance. Steph Curry is having an MVP-caliber year, Klay Thompson is playing at an All-Star level, and their role players have taken several steps forward to plug the gaps.
But it's the defense that has truly carried this team to another level of greatness, as the Warriors currently have a league-leading 96.2 defensive rating.
The Warriors have clearly improved on that end of the floor over the last several seasons, but the switch to Steve Kerr from Mark Jackson at head coach came with several noticeable changes schematically.
The most obvious and written-about shift has been the constant switching, as Golden State trots out multiple small-ball lineups that can switch any combination of on-ball or off-ball screens from point guard to power forward.
Switching picks is not a new technique to defend screens. Particularly away from the ball on single or double stagger screens—when one or two bigs set angled screens toward the corner for a guard who either curls toward the rim or pops to the three-point line—the Warriors communicate their way through flipping assignments.
Notice how Harrison Barnes and Thompson switch an initial back screen here. On the second action when Terrence Ross of the Toronto Raptors comes off the double stagger, Thompson gets hung up and Draymond Green immediately recognizes the trouble before leaping out to contest the jumper.
Thompson, instead of continuing to chase and leaving two players on one Raptor, holds and takes Green's man.
The latter portion of this example is the real key to switching. The back screen to start the play is an easily recognizable switch opportunity, and most teams have a policy of switching back screens anyway. It's about staying focused mentally and making the proper adjustment instantaneously, with both teammates recognizing the proper audible and executing it flawlessly.
Most teams, however, avoid switches because it creates mismatches that can be exploited.
The New York Knicks under Mike Woodson were a switch-heavy team, but they were often exploited by opposing guards blowing by their bigs or tough rebounding situations where guards have to box out bigs.
The Warriors have the luxury of multiple like-size players, including Barnes, Thompson, Green, Shaun Livingston and Andre Iguodala. All of them are athletic enough to guard multiple positions.
This gives them a distinct edge defensively because an aggressive, like-size switch is kryptonite to most offensive sets.
Smarter teams have been putting Curry in more screening actions as a mechanism to create bad mismatches and to counter these switches, but even Curry has shown an improved ability to ratchet up ball-pressure as a counter to bigger players.
This requires opponents to walk him down into the post if they want their size advantage to become a factor. But by the time that action develops, the Warriors can quickly scamper back into more friendly matchups or simply throw a double-team at the ball.
Even more crucial to the Warriors' defensive success, however, has been their early transition cross-matching. The like-size flexibility masks some of the typical holes found in most half-court defenses, but it's in those three or four seconds during transition that its utility becomes even more apparent.
Simply put, Golden State does not get punished by cross-matches as often as other teams.
Two things occur in transition that can hurt a team's ability to defend. The first is that, in an attempt to properly match up according to the coaching staff's wishes, a defender who gets caught trailing the play cannot recover in time and his man is never accounted for by a teammate.
The second is more common and less readily avoidable. A transition cross-match becomes a liability when the offense pulls the ball out and runs something in the half court. While it's useful to prevent an easy and quick bucket, it will ultimately be exploited if the offensive team recognizes it.
After Thompson turns it over on the play below, Barnes briefly shadows Toronto's Kyle Lowry in an almost-cross-match before Thompson recovers. Barnes then heads over to Ross.
Because Marreese Speights is late getting back and Green must deal with Jonas Valanciunas rumbling down the paint, as well as the already lane-established Amir Johnson, he gets pinned behind Johnson on the post entry as he hovers between two Raptors.
Curry doubles the ball to help out, leaving his cross-matched man, Landry Fields. Johnson then fumbles the ball and throws it out to Ross. Curry and Barnes negotiate a quick switch to create a more appropriate guarding situation, followed by a late-clock Curry-Thompson switch.
In short, Golden State's switching and defensive aptitude completely wipes out the offensive blessing of transition chaos.
The other half of Golden State's schematic tinkering has been how they've bottled up the pick-and-roll. They're fourth in the league handling pick-and-rolls (including shot attempts from passes out of pick-and-roll), giving up a stingy 0.854 points per possession, according to Synergy Sports (subscription required).
Kerr's philosophy is to keep the ball on one side of the floor and push over from the weak side. In pick-and-roll terminology, this means his players "ice" the pick-and-roll, a tactic other teams term "blue," "down" or "push."
What this means tactically is the on-ball defensive guard forces the ball-handler away from the middle of the floor, and therefore makes him reject the screen. The defensive big sits in toward the sideline, anticipating the ball being pushed his way.
The guard then fights to trail or move hip-to-hip with the ball-handler, meaning two defensive players are shadowing the ball down toward the corner. This cuts off any pocket passes to a rolling big while also containing the basketball.
Most offensive bigs react by popping, and the defense adjusts by having a weak-side guard sit in on the nail (the center of the free-throw line) to stunt at the potential throwback or fully rotate over.
Here are a few examples of the Phoenix Suns executing the ice.
What's atypical about the Warriors' approach isn't that they ice the pick-and-roll; it's that they do it everywhere possible. Most teams reserve this coverage for side pick-and-roll action, simply because it's difficult to contain the basketball in an ice when the play occurs near the slot (the imaginary line extending the paint perpendicular to the baseline), middle of the floor or well above the three-point line.
Check out how high and centered they ice this pick-and-roll against the Los Angeles Clippers:
Klay Thompson is near half court with his body completely parallel to the sideline. He's literally inviting Chris Paul to go left and attack Speights.
Meanwhile, the rest of the Golden State defense pushes over toward the ball extremely far. Green, the defender on the nail, is actually on the strong side of the floor and well off his man, Blake Griffin. Barnes has completely slid over into the paint and is more than 20 feet from the weak-side corner shooter.
Curry, per most team's defensive rules, only stunts at the ball before quickly recovering to the strong-side corner shooter. In short, Paul is looking at a wall of defenders when he attacks the paint. Green actually sinks in beneath Paul's penetration, leaving him with nowhere to go.
Sure, he could kick the ball out to Griffin for a 20-foot jumper, but that is what Golden State wants. Paul ignores this option and takes a difficult step-back jumper instead.
Above all else, Golden State sticks to its defensive principles at all times. There is constant communication between defenders; all pick-and-rolls are iced if possible; switches are on time and instantaneous.
Developing this type of chemistry takes time, and it's fortunate for Kerr that most of his players have been together for multiple years.
Curry, Thompson and the rest of the offensive crew will find a way to generate shots. But when the game slows down as more defensively capable teams advance, it will be first and foremost about stops.
Come playoff time, it will be the defense that carries Golden State to a deep run.