From the start of a season in which they knew they would be outgunned on a regular basis, player development has been the No. 1 priority for the Nets under the new regime headed by general manager Sean Marks and coach Kenny Atkinson. But whenever the Nets’ “performance team” rests a healthy player, as it did Friday night with starting forward Trevor Booker in Cleveland, it raises competitive issues about whether the Nets are giving themselves the best chance to win.

No one has been affected by the new policy more dramatically than franchise center Brook Lopez, who has missed three of 29 games while healthy, including a loss Tuesday in Toronto. At times this season, Lopez has shown some frustration with his playing-time limits. He has played the good soldier in making required changes, but he admits it’s not always easy to handle.

“I’m definitely a competitor, and so it’s tough for me to do,” Lopez said of his “rest” games. “I just want to be out there on the floor with my guys in the trenches. So it is difficult. I understand it, I get it. Logically, I understand what we’re doing, but it’s tough to separate the brain and the heart in that situation.”

Booker will return to the starting lineup against Charlotte on Monday night at Barclays Center, but his absence definitely was felt by the Nets in terms of rebounding, defense and energy against the Cavaliers. Were they going to pull the upset? Likely not, but it became far more difficult without Booker.

“When we have to sit Book in a situation like this, it’s a chance for a young guy to come in and take advantage of the opportunity and do something with it,” Lopez said. “As unfortunate as it is — obviously, we need Book — one of the young guys has to be ready to step in and take advantage of that situation.”

After the Nets fell behind by 46 points in the third quarter in Cleveland, Atkinson pointed to the play of several young players who rallied to cut the final deficit to 20 points as a positive. At the same time, he acknowledges that lineup instability has contributed to turnovers and poor play in general, as well as injuries.

In their current five-game losing streak, the Nets have used four different starting lineups. “I think it’s up to our guys that come in who have the opportunity,” Atkinson said. “They have to get on the same page as the guys that have been playing. The more time they get out there, the better that will be. We’ve kind of put health and performance above everything. It’s up to the coaches. We’ve got to figure out how we integrate those new guys and do a little better job there.”

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This year, Atkinson has cited progress made by young players such as Isaiah Whitehead, Caris LeVert, Rondae Hollis-Jefferson and Anthony Bennett as evidence of the value of playing time as a major factor in development.

“You can do all the development you want,” Atkinson said, “but if they’re not playing, it doesn’t work.”

The Nets aren’t alone in resting healthy players. It’s an NBA-wide trend. But on those nights when they are undermanned by choice, the Nets simply have to hope the practice pays future dividends. “Yeah, absolutely,” Lopez said. “I get it. I understand for sure.”