Much has been said about the Nets’ talent shortage, and they can’t just turn journeymen into stars or D-Leaguers into dominant players. If they plan to exceed expectations — as low as those expectations are — they will have to do it defensively, and that’s where they started on new coach Kenny Atkinson’s first day of camp.

“I definitely come from a program that really made an emphasis on team defense,” Atkinson said. “The challenge is for me to find out what fits our players, what fits Brook Lopez as opposed to Al Horford. It’s not easy to overachieve in the NBA, but if there is a way to do it, we can do it with great team defense.”

Atkinson’s Hawks teams thrived on defense, while mediocre defense would be a huge improvement for the Nets. And getting improvement from Lopez, their best player, will be a big key.

Atlanta had the best field goal defense in the NBA (43.2 percent) last season, while the Nets were dead last (47.9) en route to the league’s third-worst record. It’s no wonder they spent the overwhelming majority of their first day of training camp under Atkinson working on defense.

“We’re trying to implement a lot of our defensive stuff the first day,” Atkinson said. “Sixty to 70 percent was tilted toward the defense. We need to be clear on what we’re doing right from the first day. It’s the first thing we addressed. Transition defense is huge today in the NBA. That’s where it starts.

“Teams want to score early in the shot clock, so getting your transition defense set, and then it’s your pick-and-roll defense. In the NBA there are pick-and-rolls coming everywhere, so giving our guys a comfort level and right off the bat saying that’s what we’re doing in those situations.”

Atkinson and general manager Sean Marks are hoping adding versatility and length in the backcourt (and more discipline) will help in both transition and the pick-and-roll.

“The more activity and length we can get on the ball it’s definitely a big help. [Jeremy Lin’s] size is helpful. … Him and Greivis [Vasquez] in the game together definitely gives us more versatility,’’ Atkinson said. “Then you’ve got Sean [Kilpatrick] and Rondae [Hollis-Jefferson], who can even switch with our bigs, he’s that versatile. That’s a plus.”

Hollis-Jefferson (6-foot-7), Vasquez (6-6), Kilpatrick (6-4) and Lin (6-3) give the Nets length in the backcourt, and Hollis-Jefferson’s defensive plus-minus (2.6) would have qualified for the league’s top 20 if he had logged more games. But they will have to be on a string defensively for that length to help.

“We have to all have that type of trust to know that next guy in line has our back on the defensive end,’’ Kilpatrick told The Post. “We’ve got to have one of those teams that’s a loud team. When you have a loud team, it’s hard to score buckets against them because everyone’s on one chord.”

Under-the-radar signing Trevor Booker’s 2.3 defensive plus-minus was in the top 20. That interior defense is much-needed, with pick-and-roll defense having been Lopez’s weakness throughout his entire career.

“I’m always looking for ways to improve and challenge myself … I’m not a perfect player and I’m absolutely looking forward to this opportunity,’’ Lopez said. “There’s no question that’s somewhere I look to get better. … Being better in pick-and-rolls, better at covering guys on the perimeter, whatever he needs from me, I’ll do it.”

Moving his feet better on the pick-and-roll is one area of improvement. Lopez’s listed weight is down just 7 pounds from last season, but he’s visibly leaner and, according to the Nets, more agile.

“I know he’s coachable and I’m convinced he’s capable. So now it’s up to the coaches to get the scheme that’s going to fit [him],” Atkinson said.

“You need to be able to move as a big defensively. He’s made a commitment to improving his body, his mobility, his agility. That’s going to help him on the defensive end. He’s a smart player; if you’re smart and you can move, you should be a pretty good pick-and-roll defender.”