Brad Stevens has a long history of coaching underdog teams to greater success than anyone expects. He led a mid-major Butler program to back-to-back NCAA title games and a Celtics team with just one healthy All-Star (Al Horford) to back-to-back Eastern Conference finals. But this season is different. Boston entered 2018-19 as the favorite in the East. And for the first time in Stevens’s coaching career, his team is underwhelming and underachieving. Through 20 games, the Celtics are 10-10, with an offense that ranks 27th on the season and a normally elite defense that ranks eighth over their recent 4-8 stretch. Stevens has worked his magic to make ordinary teams special; now he has a new challenge: to help the most talented team he’s ever coached meet its extraordinary expectations.

“It’s not one guy. It’s not two guys. It’s all of us,” Stevens said last week. “We’re not playing with the same personality we played with last year. That’s the easiest way to describe it. And then the 50,000 issues that are below that. We have to tackle one at a time.”

Stevens should start with his offensive system, which has hasn’t changed much over his six seasons with the Celtics. Subpar scoring has been the norm for them; they’ve finished higher than 13th in half-court scoring only once, in 2016-17, according to Synergy. It was excusable in the past, when Jeff Green and Evan Turner were leading shot takers, but not now, with a deeply talented team led by Kyrie Irving.

Shot selection is a primary cause of the scoring struggles. The Celtics attempt the highest frequency of open shots in the NBA, but their problem isn’t just a matter of missing them. Quality matters. And so far, too few of their attempts are layups, and too many are midrange jumpers. The Celtics attempt 32.4 percent of their shots from midrange, the 13th most in the NBA, and 15.8 percent of shots from midrange outside 14 feet, the seventh most. They also draw the seventh-fewest fouls and attempt the third-fewest shots at the rim, ahead of only the Warriors and Spurs. The Warriors also shouldn’t settle for a league-high number of their shots from midrange, but they can get away with it because, when healthy, they have three of the greatest shooters ever. The Celtics don’t; so they need to prioritize pressuring the rim to generate efficient shots.

Midrange attempts from Irving or Jayson Tatum are understandable late in the shot clock when few good options are available. But there are plenty of low-quality shots that Boston can eliminate from its diet.

Boston’s on-ball screens and handoffs are too often set just inside the 3-point line, which positions the ball handler to attempt a long 2, not a 3. In the clip above, Horford’s handoff to Irving occurs inside the line, which doesn’t give Irving space to pull up from 3. Since defenses will happily allow midrange jumpers, there’s no reason for the big man defender (Jusuf Nurkic) to step up to prevent a shot. As a result, help defenders don’t need to crash into the paint, and Irving has a much more difficult route to penetrating or passing to the rolling screener.

The Celtics don’t use much of the pick-and-roll. They finish only 27.3 percent of their possessions that way, seventh lowest in the NBA. But tweaking the positioning of the screener could propel them from the middle of the pack in scoring efficiency (11th) to the top of the league. Damian Lillard and Kemba Walker have games comparable to Irving’s, and the Blazers and Hornets routinely rank near the top of the NBA in pick-and-roll volume and efficiency. Both almost always have the big man set an on-ball screen outside the 3-point line, like Nurkic does in the clip below for Lillard.

The screen is set a few steps above the 3-point line to allow Lillard room to get off a 3. The Warriors’ big man defender drops to prevent the drive, and Lillard easily pulls up. Defenses are often forced to adjust against dynamic scoring guards by having the defender “show” or “hedge”—i.e., stepping up to deter the ball handler long enough for their teammate to recover—which can create open rolling lanes for the screener. Watch Hassan Whiteside step up on Walker, who hits Cody Zeller for an open layup.

Forcing the defense to scramble to protect the 3-point line opens up opportunities at the rim. It’s not like Celtics don’t ever set screens this way, but they don’t do it often enough.

Stevens can apply the same adjustment to screens set for off-ball actions.

In the first clip against the Knicks, Tatum should have attacked the basket. Enes Kanter isn’t a rim protector, and if the defense had collapsed on Tatum’s drive, Horford or Jaylen Brown could’ve been open for 3. In the second play, against the Hornets, Tatum made the shot, but Horford was wide open behind the arc. The results are less important than the process. These plays are designed to generate 2-point jumpers, not layups or 3-pointers.

By asking the big to set the screen closer to the free throw line extended, Tatum would be forced to sprint through the screen at an angle that gives himself a chance to unload a 3 off the catch, rather than curling to the middle of the floor. Tatum has shot 10-for-20 on 3s off screens in his career, but he doesn’t do it enough. Watch how the Nets set screens at the free throw line extended for Joe Harris, a stellar 3-point shooter off screens:

Stevens has made subtle changes before that have helped the Celtics’ shot selection. Boston ranked near the top of the NBA in long midrange attempts over his first two seasons as Celtics head coach before ranking near the bottom during the 2015-16 and 2016-17 seasons. Bigs began setting screens and initiating dribble handoffs farther away from the rim, and shooters took side dribbles into 3s instead of midrange pull-ups.

Those systematic changes were most apparent in the play of Avery Bradley, who went from taking about half his shots from midrange to less than 40 percent, according to Cleaning the Glass. Bradley exchanged midrange attempts for 3s and attempts at the rim, and it fueled the best scoring seasons of his career. But over the past two seasons, as the rest of the league has increased the number of 3s taken and decreased the number of midrange jumpers, Boston’s frequency of midrange attempts has stayed the same. The Celtics are taking slightly more 3s than they did the past two seasons, but they’ve come at the cost of at-rim chances, which remain the game’s most valuable shot.

Boston once had a progressive shot distribution, and it created those shots with heavy ball movement. But the Celtics rank in the bottom half of the league in passes per game for the first time during Stevens’s tenure. It shows in the number of midrange attempts they take early in the clock, when there’s still time to seek a higher-quality shot.

Both attempts—by Terry Rozier and Brown—come with at least 14 seconds remaining on the shot clock, when there’s no reason to settle. It often seems like players are pressing. When Stevens talks about the team’s “personality” changing, what he means is that the level of togetherness isn’t like it was in previous seasons, when players sacrificed for the greater good and looked for the extra pass to go from a good to a great shot.

Stevens has chosen to give Gordon Hayward more touches because he’s a better playmaker than Rozier and a more seasoned scorer than Brown. But those two are being asked to take a backseat after helping lead the Celtics to the East finals. It can’t be easy to see your role plummet, especially when so much money is on the line. Next summer, Rozier will be a restricted free agent, and Brown will likely hit restricted free agency in 2020. But that’s no reason for bad habits to reemerge. Brown is taking wild shots and making careless plays on offense, just like he did at California. Rozier looks like he’s back at Louisville giving Rick Pitino heart attacks by stopping the ball, ignoring open shooters, and launching contested midrange shots.

Stevens could strike a better balance between Hayward’s return and the development of his young players by putting the star on the floor for fewer minutes, making him earn playing time rather than being granted it like he’s the teacher’s pet. Hayward has been second on the team in minutes (29.9) since November 11, when he cracked 30 for the first time since he left Utah. But as much as Hayward has struggled this season, it’s also tough to blame him. He took nearly 16 shots a game with a usage percentage of 27.6 in his last season with the Jazz; this season, he’s shooting only 9.2 times per game with a usage percentage of 18.4. Hayward isn’t at full strength; he is reluctant to draw contact in the paint, lacks explosiveness, and is struggling to shoot off the dribble. But he is deferring because he understands his limitations—which is what Rozier and Brown could learn from. If Rozier wants to get paid nearly $20 million annually, chucking midrange jumpers isn’t the answer.

In past seasons, Celtics players have spoken about the freedom that Stevens afforded them to play their games. The system helped turn Jae Crowder into a solid offensive player and Evan Turner into a $70 million man. But those rosters lacked the star talent that Boston has today with Irving, already an established superstar, and Tatum, a blossoming star scorer. Perhaps establishing a clear offensive hierarchy could help players like Rozier and Brown settle into defined roles and assure that the players who should be shooting are actually doing so.

Too often, Boston’s best scorers aren’t the focus. And while Stevens isn’t totally to blame for all the ugly pull-up 2s players have taken early in the clock, this isn’t the first time this has happened under his watch. Marcus Thornton used to resort to playing hero ball when he was with the Celtics for the first half of 2014-15, and, even today, Marcus Smart, one of the NBA’s worst high-volume 3-point shooters in history, launches contested shots. Irving could use one or two more shots per game (17.8), and Tatum can shoot more than 13.1 times per game. Tatum might be only 20, but he can score from anywhere on the court using any play type. Boston has a lot of talent on its roster, but Tatum needs to be featured.

The lone season when Boston force-fed its star scorer was in 2016-17; Isaiah Thomas had one of the most efficient high-volume scoring seasons in NBA history while averaging 28.9 points on 23.1 true shot attempts. Thomas was empowered to be the alpha, and the rest of the team fell in line. That roster cut far more frequently than any of Stevens’s other Boston teams (13th in cutting frequency, according to Synergy, and never higher than 22nd in any other season), as Thomas frequently found Crowder, Amir Johnson, and others diving to the rim. The Celtics finished fifth in half-court scoring efficiency that season, according to Synergy, and they wouldn’t have had that success had the offense not been funneled through Thomas. Stevens can take a page out of his own playbook: Feed Irving and Tatum; ask Brown, Marcus Morris, and other role players to take advantage of secondary on-ball chances and cut from the perimeter off their primary scorers’ attacks.

Thomas’s breakout was also aided by Horford’s spacing and playmaking. But Horford has underperformed this season; he’s hitting only 32.4 percent of his 3s and struggling to score from the post. But the greater concern is his declining pick-and-roll defense.

Horford has been one of the NBA’s elite defenders for years; he could comfortably switch onto guards and alter shots around the rim using his long wingspan. In the 2018 playoffs, Stevens asked Horford to guard Giannis Antetokounmpo, Ben Simmons, and Joel Embiid—three stylistically different players. Horford had success against each. This season has been a different story. He has had great moments on defense, but he’s been shredded more frequently on switches against smaller players.

Horford has been Boston’s anchor on defense, but he has looked slower moving laterally this season. He’s missed one game with a sore knee, so he may be physically limited. But he’s 32 years old and has a lot of miles on his legs, including 10 playoff appearances in 12 seasons.

Defense is never a one-man job, though, and as the Celtics’ offensive struggles have worsened, the frustration has manifested on defense. The team isn’t staying focused: It’s missing off-ball rotations, and its on-ball communication has suffered. Sometimes, one player is looking to switch or show while another is looking to ice a screen:

The Celtics need Horford to be better by the playoffs, and they need to make systematic changes to put him in better positions to succeed. After a 113-104 loss to the Mavericks on Saturday, marking Boston’s fourth defeat in five games, Marcus Smart succinctly summarized the difference this season: “Lack of effort. Lack of fear. We don’t impose our fear and will on other teams,” Smart said. “Teams knew they were in for a fight [last year]. This year, teams can’t wait to play us. That’s a problem. When guys aren’t scared of you anymore there’s nothing you can do about that.”

While Boston hasn’t been as feisty defending this season, the lack of fear could also be a result of the lack of size the team’s been putting on the floor this season. Horford played 53.8 percent of his minutes with another big man last season, but has logged only 30 of his 568 minutes (5.3 percent) next to another big this season. Few other big men have shared the floor together. Without much size on the floor, opponents are finding ways to attack the rim.

In this clip, DeAndre Jordan aggressively rolls to the rim, which leaves Tatum on an island. Tatum has no choice but to foul Jordan. If the Celtics played with two big men, Aron Baynes or Daniel Theis would be the one helping inside instead of a smaller wing.

Stevens’s preference of using lineups with two- or three-guard combinations also creates issues on the perimeter. Irving usually doesn’t start trying on defense until late in the game, and Rozier has been disastrous defending one-on-one and in pick-and-rolls while dealing with a nagging knee injury. Stevens should try giving two-big lineups more of a chance to improve the defense, and, instead of distributing touches among four perimeter attackers, he should funnel more of the offense through the team’s best playmakers.

Despite all of their struggles so far, the Celtics are still in one of the league’s most enviable positions. They have the talent to make a Finals run this season and the youth to keep winning into the next decade. Boston shouldn’t panic. Using Rozier as trade bait would be logical since the team has better playmakers, and maybe a team that could use a young playmaker, like the Suns, would be willing to flip an asset like Josh Jackson to get him. But most executives expect the trade winds to stay quiet, and there are few players who would realistically be available who would be upgrades for Boston. The Celtics’ best approach is to sit on their war chest and wait for a player like Anthony Davis to become available, which likely won’t happen until this summer at the earliest. The Pelicans will do everything in their power to keep Davis until then; and, besides, the Celtics wouldn’t be able to trade for Davis until Irving opts out of his current deal this summer, because teams aren’t allowed to trade for more than one player signed to a Rose Rule contract.

In the meantime, the roster has enough talent on paper to not warrant any major changes. A few tweaks from Stevens and the coaching staff could make a world of difference. Before the Celtics think about pressing the panic button, they first need to figure out how to maximize the potential of their most talented roster since Stevens arrived six years ago.