- Celtics head coach Brad Stevens is revered for his basketball mind, with players and peers lauding his after-timeout plays. The Crossover takes you inside the simple science behind his sets.
If the work of a basketball coach is to best position his players to succeed, the after-timeout play (or ATO, in coaching parlance) is the literalization of that work. It’s in those scenarios that micromanaging can be put to best use: a coach can position the chess pieces as he likes and move them along carefully scripted lines. Between that underlying scheme and the intuitive reads of the players involved, ATO offense can bridge any number of limitations to create a quality shot.
Brad Stevens, the revered head coach of the Celtics, uses that medium as effectively as any coach in the league. The structure of Stevens’s ATO sets works almost like a sixth player on the floor, forcing the defense into mistakes with shape and timing. “Brad is a genius, man,” Al Horford said with a smile in the aftermath of Game 3 against the Sixers—a game that Stevens’s play design helped to secure. “Unbelievable.” There is no magic to what Stevens does with a clipboard. Rather, he layers simple actions in intelligent ways, informed by a detailed understanding of what his players are capable of. See for yourself:
This was easily the most high-profile of Boston’s ATO plays this postseason, and for good reason. In theory, having the time and freedom to draw up a play should result in the offense creating some sort of clean look. In practice, the idea of executing an inbound play against a set defense with the game on the line and only a five-second count to work with is much more challenging than it seems. With this particular set, Stevens empowered the Celtics to be ambitious but conservative; setting up a good scoring opportunity off of a single pass suits the risk-averse nature of these sorts of possessions, but the way Boston got there was undeniably creative.
Let’s reverse engineer this set based on its final result: How could a team, on a game-deciding possession, convince four opposing defenders to clear the paint after creating a clear mismatch in the post? The critical juncture of this set is the jumble Boston creates on the right block. It’s there that three Celtics converge: Jaylen Brown, who was set up in this space as the play began; Jayson Tatum, who darts in from the far corner to set a baseline screen on Brown’s defender (Ben Simmons); and Horford, who comes down from the elbow to set a second screen on Simmons, this one perpendicular to Tatum’s. It would require a feat of incredible defense for the Sixers to get through this action without having to switch to cover Brown. And by virtue of where Brown moves (up toward the top of the floor), it makes the most sense for Horford’s man (Joel Embiid) to pick up the switch.
That explains the origin of the mismatch. Tatum, for his part, continued through his screen by effectively hugging Simmons and dragging him out to the three-point line—and away from the post. Marcus Morris, who is inbounding the ball from the sideline, moves only to step back on the court after delivering the pass to Horford. By the time his defender (Ersan Ilyasova) turns to see where the pass is headed, he is in no position to help. That accounts for four defenders, but where is the fifth? He’s chasing Terry Rozier out past halfcourt and out of the broadcast frame, clearing two more bodies out of Horford’s way.
Every Sixers defender was so locked in on a single opponent that they lost sight of the bigger picture. It’s hard to blame them; given what teams run in endgame situations, playing tight, attentive individual defense is a reasonable strategy. Switch as needed, cover your bases, and make whatever shot comes as difficult as possible. Yet in this case, it also results in the same collective moment of realization as the ball sails into Horford’s hands with nothing to stand between him and a go-ahead layup. The Sixers were had.
Not content to let Game 3 ride on a Morris isolation, Stevens actually called for a timeout mid-move to draw up this set during the final minute of regulation. We can see from the way that Ilyasova hands off responsibility for Horford to Embiid that the Sixers are prepared to switch everything on this possession. Yet what makes this set so clever is that it is effectively switch-proof. Brown sets a second screen on Ilyasova that triggers yet another switch, though the way that screen is positioned leaves no defender between Brown and the rim. It’s the switch that actually creates the opportunity for the lob; with a subtle turn, Brown creates all the buffer he needs to collect the pass from Tatum and finish at the rim.
A crucial part of drawing up a productive set is understanding how the action will fit into a defense’s expectations. Offense in the NBA is so widely imitated that players are programmed to anticipate certain movements, whether they realize it or not. Simmons does that on this possession. Watch as Rozier makes his cut through the paint and toward Tatum in the corner. In the vast majority of cases, a player in Rozier’s position would make that cut to set a baseline screen for Tatum. You can actually see Simmons slow down when he realizes where Rozier is going… only to be caught out of position when Rozier suddenly veers up toward the top of the floor instead. Horford is already in position at the elbow to screen off Simmons from recovering, setting up Rozier with a clean look.
What makes ATO offense so challenging to guard is the precision of its choreography. A stoppage in play gives every player time to find their spot, and the initiation of that play allows for a much clearer trigger than other offense run in the flow of a game. When executed well, these sets force defenders to make split-second calls to contain multiple threats, each spinning off in a different direction.
The action of note, in this case, is Horford’s screen for Tatum. Morris has already curled around that same screen in somewhat casual fashion; Morris never sells his cut as if he were actually a threat to receive the ball, which, in a way, only draws more attention to Tatum. Running consecutive players around the same off-ball screen is a common premise for NBA offense, and Boston’s positioning on this play makes Tatum’s intentions abundantly clear. In doing so, the Celtics entice Ilyasova to cover Tatum as he rounds the screen—losing track of Horford as he slips through the back door. You can actually see Rozier, who is handling the ball on the opposite side of the floor, call for the slip when he sees both defenders commit to Tatum.
There’s a simple elegance to a set like this. Once Morris makes his cut through, Tatum and Horford have an entire side of the court to themselves. That means that even if the Sixers defend every action perfectly, the Celtics are still set up for Tatum to attack Marco Belinelli in a well-spaced isolation. The best sets aren’t designed to create one single scoring opportunity. They create options, and if all else fails, they put the offense in a position to find its footing quickly.
Boston’s sets aren’t merely functional—they’re adaptive. This particular look takes a few common elements of the Celtics’ offense and punches them up with a targeted matchup. Philadelphia has selectively cross-matched Embiid against Morris in this series, primarily to mitigate the damage of Horford’s pick-and-pops. Boston counters first by feigning the obvious (a post-up for Horford, now that he’s guarded by a slighter defender than Embiid), and then by using Morris as a screener for Tatum at the top of the floor. Embiid intends to switch this outright, while McConnell—in an attempt to keep his center out of a one-on-one matchup against Tatum—tries to scramble back. The result is an uncontested three for Morris, as Horford first surveyed to see if Tatum might be open, and then quickly redirected to the open man.