PHOENIX -- Boston is in a bit of a funk after losing the first two games of its five-game road trip, and a frustrated Kyrie Irving is out $25,000 after throwing a ball into the stands after the latest loss in Denver.

Phoenix's troubles appear to run a lot deeper, however, as the Suns prepare to host the Celtics on Thursday in the final game of a five-game homestand at Talking Stick Resort Arena.

The Suns (2-8) have lost eight of their last nine and appear in danger of falling into irrelevancy for the fourth straight season after a 104-82 loss to Brooklyn on Tuesday, a defeat that brought energy and chemistry issues to the fore.

Suns leading scorer Devin Booker was pointed in his criticism afterward, when asked about how to improve what appears to be lax effort saying: "Holding each other accountable and being OK with that.

"I think all good teams have that trust and chemistry where everybody can get on each other and know that it is for a better purpose. So far I don't think we have that right now," he continued.

"We're not comfortable with each other. We don't step on each other's toes. We don't push each other, and I think that's what we need to do. We came in here and got (blown) out in front of our fans, so it's embarrassing."

Booker had a team-high 20 points against the Nets, but he was only 6-of-21 from the field as the Suns shot a season-low 34.6 percent.

The Suns have committed 18.5 turnovers per game, ahead of only Atlanta, and opponents are shooting 50.1 percent from the field, a head of only Cleveland. The Suns have lost five games by at least 20 points and one by 18.

With four new starters and new coach Igor Kokoskov, a feeling-out period should have been anticipated, even expected. But Koskokov again Tuesday questioned the effort level of some of his group, not the first time it has come up.

"Focus wasn't there," Kokoskov said. "Body language wasn't there. Effort wasn't there. We have to find that greed and that energy. That's what we control. This is a team sport, not an individual sport.

"Without each other, we can't get it done. It requires everybody to be engaged."

The Suns continue to tinker with playing time and rotations in an attempt to find a workable mix. Richaun Holmes, the backup center now that veteran Tyson Chandler was bought out, had season highs with 13 points and 10 rebounds against the Nets, and rookie reserve forward Mikal Bridges saw more time than starter Ryan Anderson.

But Josh Jackson, the fourth pick in the 2018 draft, saw his playing time shrink again, playing only seven minutes. He has played 31 minutes in the last three games, with 21 points and seven turnovers.

"There are going to be times when things don't go our way, but our energy and effort can never be questioned," Holmes said.

"That's a requirement."

Boston has had two days off since suffering a 115-107 loss at Denver, when Nuggets guard Jamal Murray scored 48 points. It was Murray's last-second attempt to reach 50 that made Irving upset enough to throw the game ball into the stands. Hence the fine from the league.

"The ball deserves to go in the crowd after a bull(xxxx) move like that," the world-is-flat Irving said at the time, "so I threw it in the crowd."

"I felt disrespected after the game, so your career-high ball goes in the stands," he said after the fine.

The Celtics (6-4) finish their season-long five game trip with games in Utah on Friday and Portland on Sunday.

Irving tied his season high with 31 points and Gordon Hayward had a season-high nine rebounds against Denver as the two continue to push through the early portion of the season after missing significant injury time a year ago.

Irving is averaging 19.2 points, one of six Celtics scoring in double figures. Hayward is averaging 10.1 and 5.8 rebounds. Jayson Tatum, the third player taken in the 2018 draft, is averaging 15.7 points and 7.2 rebounds.

The Celtics received a surprise visit from Peyton Manning in Denver on Monday. Manning and Celtics coach Brad Stevens are friends from their time in Indianapolis when Manning was with the Colts and Stevens coached Butler. Manning watched film and spoke to the team.

"It's great, man," Irving told the Boston Globe. "He's a championship winner. Unbelievable preparer of the game. He was doing it for so long, thinking about the injuries he had to endure.

"It was great to see him just come and talk to your team ... just having an echelon of greatness coming and talking. There's nothing like it."