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Video breakdown: Celtics motion offense

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The Celtics boast one of the most talented collection of wing players. So how does Brad Stevens choose to employ the size, athleticism, and versatility of that core?

NBA: Toronto Raptors at Boston Celtics Winslow Townson-USA TODAY Sports

There’s little doubt 60-games into the season the Boston Celtics are firing on all cylinders. The young guns have leveled-up and become All-Star-caliber wings. Gordon Hayward has bounced back in a big way. The emergence of Daniel Theis as the perfect center for this team eliminated a trade deadline overpay. Things in Beantown are going quite well.

Don’t take that for granted. It wasn’t too long ago when the Celtics’ starting point guard was sucking the life out of the Garden and this organization. His presence disrupted the natural rhythm and flow of Brad Stevens’ offense. While the Celtics were winning, there wasn’t a cohesion to their group, nor the aesthetically pleasing nature that accompanies a team who shares the ball.

Stevens has rebuilt that culture revived this offense all in one season. The set plays he runs allow him to dial up play calls to exploit certain match ups or feed the hot hand, but the NBA is much more free-flowing than a coach-controlled game would allow. What Stevens’ biggest accomplishment this season has been is creating a base offense that simultaneously dissects its opponents and enables its actors to improvise.

The motion offense begins with a strong-side cut from the point guard, usually Kemba Walker or Brad Wanamaker. He’ll dribble up the floor and push one teammate through to the opposite corner. He’ll then replace that teammate, pass to the wing, and cut to the corner.

It may sound cheesy, but having two cutters before the ball enters the 3-point line does wonders for the Celtics’ ability to create movement among the defense. Think of it like a wide receiver moving in motion before the snap: it moves the defense to either reveal their coverages or shift each player into a different position than they intended.

Rule #1 within the Stevens offense: everyone 1 through 4 is interchangeable. The big runs the floor, and everyone else knows and fills the other spots. Jayson Tatum can bring it up. Kemba can run to the wing. Everyone will spend some time in every spot and that makes it really tough to guard.

Once Kemba gets to the corner, the Celtics’ 5-man (usually Theis or Enes Kanter) will pop to the top of the key and catch a reversal. That’s when the offense really opens up. The first option is a guard-to-guard split action, some combination of one screening for the other in a way that’s meant to throw off the defense with how quick it occurs:

Hand offs to open threes. Slips to layups. Post-up mismatches with the lane spread for bigger wings. Tatum, Brown, and Hayward all make a killing here because they can get into the post early and dominate small guards, aided by the decoy of an All-Star scorer like Kemba Walker in the two-man split. Every shot they generate occurs in an analytically-pleasing zone.

The guard who passes to the big atop the key is the primary decision-maker. He can cut baseline and get involved in the two-man split action. He can jump middle and get a return hand off to play.

My favorite option, though, is a cut over the top of the big to the other side of the floor, where he screens for the wing. By doing so, all five players in the action are either touching the ball or cutting through the lane in the first ten seconds of the shot clock.

This cut is often referred to as a “scissor action” because of how it makes an “X” around the big with the ball:

A scissor cut in the middle of the floor, especially when you don’t know what’s coming, is incredibly difficult to defend. Go under the screens and the big and a wing is getting a wide open try. Go over the top and the lane opens up for a rim attack. Scissoring around the big is only effective because of how rarely it’s used and that it isn’t a primary option. Every guy on the team understands the need for variety in their diet so none of the reads become stale.

Theis doesn’t need to wait for a scissor cut in order to engage the other wing and switch sides of the floor either. As soon as he catches the reversal, he can start a dribble hand off with the wing.

Hand offs when intentional and quick act like ball screens. The initiator serves as a passer and screener at the same time, and due to the speed with which a hand off happens, sticking to defensive coverages is more difficult to do.

Take note of the pace with which all Celtics bigs engage in a hand off and prevent the defense from recovering:

Let’s get into the nuances now knowing how the C’s can involve literally every player within their motion. Defenses aim to disrupt, particularly in the postseason when they pour energy and effort into scouting a singular opponent. Coaching staffs look for tells within the initiation of an offensive pattern that indicates the exact play which will occur, then design a game plan to short circuit that pattern.

While quick-hitting and effective, this offense does have areas ripe for disruption. Chief among them is the reversal to the big. Theis and Kanter aren’t exactly fleet of foot, so mobile bigs could deny their flash to the top of the key, prevent a reversal, and stall the entire offense.

Stevens is prepared. The offense clicks even when defenders jump to anticipate the flash. Theis or another big will step to the opposite wing and set a single down screen to spring open another player, and do so without much hesitation:

Good gracious this offense is fun.

There are plenty of other wrinkles and counters that Stevens can go to and the players on the floor have freedom to call. The bottom line is that we aren’t watching isolations or high ball screens possession after possession after possession. There’s a randomness to it that is consistently beautiful to watch and successful in it’s effectiveness; the Celtics boast the sixth most efficient offense at 112.6 points per 100 possessions.

The whole truly is greater than the sum of its parts.