The Celtics can't figure out how to score when Kyrie sits

Embiid scores 26, Sixers beat Celtics 89-80 (2:18)

Joel Embiid puts on a show scoring 26 points as the Sixers beat the Kyrie Irving-less Celtics 89-80. (2:18)

SAN FRANCISCO -- Boston Celtics coach Brad Stevens gave his 12-year-old son, Brady, a Christmas gift last month that any young NBA fan would covet: tickets to a Golden State Warriors game. But don't get the wrong idea about the younger Stevens' rooting allegiance.

"Let's get this straight, he was wearing Kyrie [Irving] shoes today," Stevens said Friday with a smile.

Indeed, Brady was sporting a pair of Nike Kyrie 4 "Confetti" sneakers while he and pal, Braeden Shrewsberry, son of Celtics assistant coach Micah Shrewsberry, got shots up on the campus of the University of San Francisco following Boston's offday workout.

The young duo got a brief respite from school obligations to be inside Oracle Arena on Saturday when the Celtics visit the defending champion Warriors (8:30 p.m. ET, ABC).

You'd think the biggest challenge facing the elder Stevens would be game-planning to slow Golden State's otherworldly offense, the one that captivates NBA fans of all ages while posting a league-best offensive rating of 113.8 this season.

No, Boston's biggest concern is its own offense.

Masked by both a league-best defense and a lofty spot atop the Eastern Conference, the Celtics have been the league's worst offense in the month of January, a brutal nine-game stretch in which Boston has struggled to score with any sort of efficiency.

When Gordon Hayward was lost to a fractured ankle in the opening minutes of the 2017-18 season, it was obvious that Boston's offense wasn't going to be as potent as expected. For a Celtics team that didn't have a secondary creator to pair with Isaiah Thomas in recent seasons, Hayward's addition was supposed to end the maddening lulls that often occurred when Boston had its All-Star point guard on the bench.

Right now, it's the same old story. Even though the Celtics swapped Thomas for Irving in August, Boston is enduring similar troubles whenever Irving goes to the bench. The Celtics, their depth depleted in the Irving deal, have been forced to lean heavy on inexperienced players and, not surprisingly, the results have been inconsistent. Stevens lacks the sort of secondary scoring threat that he might have been able to stagger with Irving.

Boston owns an offensive rating of 108.2 with Irving on the floor this season, according to NBA Advanced Stats. That's tied for the best on-court rating on the team with Al Horford, and is nearly four points higher than Boston's season average.

But when Irving goes to the bench, Boston's offensive rating dives to a team-worst 97.2. That means Boston is 11 points better per 100 possessions with Irving on the floor.

Boston's Irving-less struggles are particularly pronounced this month. For the month of January, Boston's offensive rating is an impossibly low 86.4 when Irving is not on the court. In the one game he missed because of shoulder soreness, Boston was held to a season-low 80 points in a loss to the Philadelphia 76ers.

Boston simply hasn't been as crisp offensively even when Irving is on the court recently. And Stevens has challenged his team to play with more effort, especially in getting to their spots quicker.

"I think we need to have more pace to everything that we do," Horford said.

So even though Boston has limited the Warriors to an offensive rating of 98.2 over the past three seasons -- an absurd number when you consider the next-best team is the Spurs at 104.2 and the NBA average against the Warriors is 113 in that span -- Stevens said he knows now that Boston cannot endure offensive lulls Saturday in Oakland.

"I think in both of those games (Boston won at Oracle) we were able to score at appropriate times to limit their runs," Stevens said. "When they go on those 8- 10- 12-0 runs, it can happen in a minute. Watching [Golden State's] game [against the Minnesota Timberwolves on Thursday], it seemed like it happened eight times. I think that these guys are so special on both ends of the floor, but you just have to try to make it a possession-by-possession game. That's a lot easier said than done."

When the Celtics ripped off a 16-game winning streak early in the season, they benefited from the offensive jolt that rookie forward Jayson Tatum and second-year swingman Jaylen Brown provided. As both have struggled at times recently, the Celtics do not have someone to lean on beyond Irving.

Horford is an All-Star in part because of the way he can help distribute the ball (he leads the team in assists) and his uptick in 3-point percentage (he ranks seventh in the NBA at 43.5 percent beyond the arc). But Horford also ranks 80th in scoring average. When Tatum and Brown have quieter nights, it's hard for Boston to find the needed offensive jolt.

Marcus Smart, who had been the team's second-leading scorer in January in a bench role, lacerated his right hand punching a picture on the wall of his Beverly Hills hotel this week and is out for the next two weeks. That means even more pressure on the likes of Marcus Morris and Terry Rozier to provide scoring.

For a team that's so stout defensively, the area of greatest concern for Stevens might be transition offense. The Celtics, more than any other team in the league, are generating consistent stops but can't seem to take advantage going the other way.

The Celtics average 1.03 points per play in transition, which ranks 23rd overall in the NBA this season, according to Synergy Sports data. More jarring: For the month of January, the Celtics are shooting a mere 46 percent in transition, per Second Spectrum data, which is easily the worst in a league where no other team is below 50 percent in that span.

It doesn't help Boston that it ranks in the bottom third of the league in free throw attempt rate (.241) and are 30th for the month of January (at a startlingly low .168).

There are no simple answers for the Celtics. The encouraging part is that they have had stretches this season where the offense has looked really crisp and, paired with an elite defense, it has helped Boston to the third-best record in basketball.

And still, Stevens can't help but look at all the scoring options on Golden State's roster and be a bit jealous. No wonder his son wants to see them up close.

"[The Warriors are] a joke. I don't even know what to say. It's so fun to watch," Stevens said. "It's a special, special group that's been assembled. And they can go on runs that are absolute killer if you're competing against them. And an absolute blast if you love good basketball. So I would just say that, when you put all that talent together, and they have such a desire to play together and enjoy playing together the way they do. Then that's what makes it fun to watch."