Celtics’ biggest defensive problem? Players aren’t in the right position

Celtics coach Brad Stevens believes his team needs to be in better position to improve defensively.charles krupa/associated press

WALTHAM — Despite the Celtics beginning to approach full health, coach Brad Stevens wasn’t in a celebratory mood after Saturday’s practice.

Stevens lamented the Celtics’ defense through the first five games, as they are allowing a whopping 109.6 points per contest entering Sunday’s matchup against the Denver Nuggets. That’s 26th out of 30 NBA teams. What’s ironic is that Boston is sixth in field goal percentage defense, meaning its pace of play is allowing opposing teams to pile up points.

Also, the Celtics are just 26th in the league in 3-point percentage defense and have yielded 56 in the first five games, including 14 to the defending champion Cavaliers. The Cavaliers took the lead for good in the first half by hitting 11 3-pointers, and Stevens refused to attribute that simply to stellar Cleveland offense.

“The No. 1 [issue] is being in the right position,” Stevens said. “Being in the right position solves a lot of things. Right now we’re not turning anybody over because we’re not in the right spot a lot. That was the case most of the preseason. We’ve had our good games. This is part of the sample size. We were awful against Brooklyn and we were awful against Cleveland defensively.”

Of course, the Celtics have missed Al Horford for the past two games with a concussion, and Jae Crowder left Wednesday’s win over the Bulls in the second quarter and missed Thursday’s loss to Cleveland. But Stevens wanted no part of excuses.

The Celtics were first in the NBA last season in forcing turnovers at 15.8 per game. This season they are 21st at 12.6. Since the Celtics are forcing fewer turnovers and allowing more 3-pointers, the defense is suffering.

“Any time we give up 128 points, we’re going to lose,” Stevens said. “My eyes, if we give up 110, we’re probably going to lose. So I think we need to get a lot better defensively and that includes finishing plays. The defense has to get a lot better.

“Now, we had some disadvantages as far as size issues, but we have to play better position then. Our position wasn’t great. Our transition ironically has been the best thing we’ve done defensively overall, which is proof that the numbers don’t always tell the truth because I don’t think we’re very good yet. We have a lot of room to improve.”

Injury updates

Horford, who took a hand to the face during Monday’s practice and suffered a concussion, was in his practice gear Saturday, taking shots and consulting with trainer Ed Lacerte, although he is out for the Denver game. The Celtics have two more days off after Sunday, meaning Horford could return Wednesday against Washington if he is 24 hours clear of concussion symptoms.

“If everything goes well, we’ll up his activity [Sunday],” Stevens said. “He will not be cleared to play for game time is what I’ve been told.”

Horford needs to be cleared to return by independent doctors.

Crowder, whose injury looked to be serious, could return by next weekend’s games against the Knicks and Pacers. Crowder underwent more treatment for his sprained ankle Saturday.

“He’s doing a lot better; the swelling is down,” Stevens said. “He’s progressing at a really good rate. As we get into the next week, he’ll have a good chance to return.”

Finally, power forward Kelly Olynyk, who has not played this season while recovering from right shoulder surgery, could return Sunday, but more than likely Wednesday against the Wizards.

“I’d say he’s closer than further,” Stevens said. “He’s going to be listed as questionable but that’s going to be completely up to him and [Lacerte’s] call. He’s getting a lot better. Like I said, he’s right around the corner here.”

Dynamic duo

The combination of Isaiah Thomas and Avery Bradley is averaging 46 points, 11.2 rebounds, and 11.2 assists through the first five games, and Thomas was asked whether the duo is among the best backcourts in the NBA.

They are competing with the likes of Stephen Curry and Klay Thompson (Golden State), Kyle Lowry and DeMar DeRozan (Toronto), Damian Lillard and C.J. McCollum (Portland), and John Wall and Bradley Beal (Washington).

“For sure, two guys from Tacoma,” Thomas said about being one the league’s better backcourts. “We’re up there. I’m not going to say we’re the best but we play and feel like we’re the best. You talk about backcourts, you can’t leave us out. That’s our mind-set this year. We’re coming for all those top backcourt guys. We’re here. Avery’s improved so much this summer with his playmaking and shooting ability and I’m trying to improve as well. So we’ve got a lot to prove.”

Thomas had nothing but compliments for Bradley.

“Avery is the best on-ball defender in the world,” Thomas said. “So that’s his niche. Me? I’m not backing down from nobody. So that’s the only thing that comes with me. I’m just going to play with my heart. We kind of have the same mind-set and go about it in different ways.”

Nuggets at a glance

■  When, where: Sunday, 7:30 p.m., at TD Garden.

■  TV, radio: CSN, WBZ-FM (98.5).

■  Scoring: Will Barton 18.0, Danilo Gallinari 16.8, Jusuf Nurkic 15.2.

■  Rebounding: Nurkic 10.6, Kenneth Faried 7.8, Nikola Jokic 7.4.

■  Assists: Emmanuel Mudiay 3.4, Jameer Nelson 3.4, Barton 2.7.

■  Head to head: This is the first of two meetings. The Celtics won both matchups last season.

■  Miscellany: This is the fourth game of a five-game trip for the Nuggets . . . Guards Gary Harris (groin) and Barton (ankle) are day to day . . . Rookie Jamal Murray, the No. 7 overall pick in the draft, went 0 for 16 from the field in the first four games of his career. Murray was 4 for 10 (9 points) in Denver’s loss to Detroit on Saturday night.