How does Boston move forward without Gordon Hayward?

The news of Gordon Hayward’s four-week absence after suffering a Grade 3 right ankle sprain in Game 1 was a crushing blow so early into Boston’s playoff run.

Hayward is not one of the Celtics’ two All-Stars. He’s not even one of the three players averaging over 20 points. But after spending all of 2018-19 trying to fit in, his play this season indicated the first sign of comfort he’s felt in Boston, and the C’s benefited tremendously because of it.

“Really tough for him and tough for us,” Brad Stevens said of Hayward’s injury. “He’s played great. I feel for him more than anything else. It’s our job to make up for all the great things he does by committee and we’ll attempt to do so.”

Usually the first guy off the bench, Marcus Smart is the logical replacement for Hayward in the starting lineup. That five-man unit has played sparingly all season but has started 10 games with a 6-4 record.

In just over 300 possessions, their defense has been stout, only 100.0 points per 100 possessions, in the 99th percentile per Cleaning The Glass. Smart may give up several inches to Hayward, but the core of his defensive prowess is the constant effort he brings, ensuring Boston remains afloat at that end.

Against the Mavericks in early November, Dallas was just 11-of-42 from beyond the arc. It was the seventh-worst 3-point shooting night on the season for a historically great offense.

Even when guarding another player, Smart is always compelled to give the extra effort if, say, a teammate’s bite at a pump fake leaves a deadly shooter open beyond the arc.

Smart spent time on just about every one of Dallas’ backcourt options in a 116-106 victory, from Luka Doncic to Delon Wright to Jalen Brunson. Against Philly in Game 1, he guarded Tobias Harris more than any other Sixer, and the 6’8’’ broad-shouldered forward didn’t even attempt a shot in that time.

As well as Smart might be able to stabilize the defense, he offers little approximation to the value Hayward brought at the offensive end.

Seven Celtics have logged more than 1,000 minutes this season. Hayward was third among them in offensive points added per 100 possessions according to CTG, behind only Tatum and Kemba Walker.

He was fourth on the team in scoring and third in assists. His ball handling and playmaking piled more layers of options for Stevens to implement. Including control of the ball in transition and even initiating screen and rolls.

For all the improvements Smart has shown offensively, with maintained improvements on his 3-point shooting and a career-high 4.9 assists per game, he’s still a minus at that end of the floor. His consistency from play-to-play is simply not something the Celtics can fully rely on. No wonder the same five-man unit that performs so well on defense ranks in just the 13th percentile on offense — per CTG.

In terms of alternatives, a bench already ranked second-to-last in scoring is about to get even thinner. Boston will likely turn to one of Semi Ojeleye, Grant Williams, or Javonte Green to get a chance to soak up some of the wing minutes Hayward left behind.

The rest, along with Hayward’s 13.5 nightly field goal attempts, should be divided up among those best equipped to handle it. Namely, the only trio in the NBA each averaging north of 20 points a game.

“We have a deep rotation, a deep bench, so whoever is going to step up, we know we are going to trust our whole team,” Daniel Theis said. “So guys are going to get their opportunities, get their minutes, and everybody has got to be ready.”

“We’re doing everything we can as the older guys, the guys that’s been here, to really get those guys ready on what to look for and what to expect when they get in the game,” Marcus Smart said. “Just be ready and not get caught by surprise.”

You wish the answer were as simple as a single plug-in, but the Celtics lack a direct replacement for a 6’8’’ do-everything point forward. That uniqueness is what makes them so dangerous.

Hayward missed twenty games during the regular season. The Celtics won 14 of them. There’s no telling what that’s worth in the playoffs, but Boston will have to lean on those victories long enough for them not to matter.