The playing-time restriction placed on Nets franchise center Brook Lopez, which is at a career-low of 26.7 minutes per game, has been a source of early-season curiosity, if not controversy. What largely has gone unnoticed is that six Nets with previous NBA experience are averaging career-high minutes in expanded roles in the regular rotation.

So, while Kenny Atkinson is focused on fixing the “defensive slippage” he blames for their recent four-game losing streak, the first-year head coach also acknowledged that a team with 10 new faces on the 15-man roster is enduring the inevitable growing pains of a rebuilding franchise. The six Nets playing career-high minutes include starters Bojan Bogdanovic, Trevor Booker and Rondae Hollis-Jefferson and key bench players Sean Kilpatrick, Joe Harris and Justin Hamilton.

“I think that’s part of it,” Atkinson said. “It’s adjusting. Let me throw myself in there. I think it’s all of us. Trevor Booker said to me the other day, ‘Coach, I’ve got to be a little more consistent.’ And the coach has got to be a little more consistent. I think it’s a challenge for a lot of us in these new roles.”

It doesn’t get any easier Wednesday night at Barclays Center against Boston (8-6) and high-scoring point guard Isaiah Thomas (26.4 points, 6.2 assists), who is yet another in a succession of elite points guards the Nets (4-9) have faced recently. Atkinson devoted the past two practice days to re-emphasizing the defensive principles that helped the Nets get off to a 4-5 start, but Boston’s Thomas represents a major test.

“Point guards today are high-usage guys, and a lot of them are scorers,” Atkinson said. “So, they’re the head of the snake, and it’s going to be a challenge again for us to make him less efficient.”

Celtics forwards Al Horford and Jae Crowder also are tough covers because of their ability to stretch the floor. Under the circumstances, the Nets’ slump could take a mental toll on a group of players who might be putting pressure on themselves to perform bigger roles, but Atkinson is confident they can handle it.

“We have a group that is committed and is really putting in the effort,” Atkinson said. “The intention is really good. What I’m really happy about is attitude, engagement, willingness to execute. I just think it’s going to take time defensively and offensively.

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“My message to these guys is: ‘How can we become more consistent?’ We’ve got to be more steady. Guys are getting used to their minutes, playing bigger minutes and playing bigger roles. Can you do it two out of three games? Can you do it three out of five games? In the NBA, it becomes consistency.”

Notes & quotes: Forward Chris McCullough was assigned to the D-League Long Island Nets to play the Canton Charge Wednesday afternoon at Barclays Center but will rejoin the Nets’ NBA roster Wednesday night, giving him a chance to become the fourth player ever to play in D-League and NBA games the same day . . . Rookie Caris LeVert did not practice Tuesday as part of the plan for his return from foot surgery but will practice Wednesday.