Since the start of training camp, Brooklyn Nets coach Avery Johnson has constantly assessed his team as a "work in progress." He uses the phrase so often that it has become something of a verbal tic, and it was there once again after the Nets beat the Toronto Raptors on Saturday night for their first win in Barclays Center.

Brook Lopez scored 27 points but grabbed only five rebounds Saturday. Associated Press

But this time around, Johnson was referring to a specific player—just not one of his rookies and not one of his reserves.

No, he was talking about starting center Brook Lopez, who largely shined in the Nets' 107-100 victory, scoring a team-high 27 points and punctuating a festive evening with a three-point play in the final minute.

For the Nets, who host the Minnesota Timberwolves on Monday, the hard truth is that Lopez is an incomplete basketball player. This isn't an indictment of Lopez. He is an asset for the Nets, who are happy to have him, or at least happy enough that they signed him this summer to a four-year, $61 million extension.

But he has never been a dynamic rebounder or defender, two areas that were training-camp priorities. Lopez grabbed five rebounds in 32 minutes against Toronto. And while one game is a small sample size, he acknowledged that he still has major room for improvement.

"I'm a little disappointed in my rebounding," Lopez said. "It's something I focused on. I thought it was there."

Lopez actually has regressed as a rebounder since his 2008-2009 rookie season. His "total rebound rate," a metric defined by as the percentage of total rebounds grabbed by a player during his time on the court, has decreased from 15.8 to 13.5 to 10.0 to 8.8 last season, when he played in just five games because of foot injuries. In theory, a 7-footer should be corralling more than 10% of the rebounds that are available to him.

Johnson said Lopez spent a lot of time this off-season with Jeremy Bettle, the Nets' strength-and-conditioning coach, and it was important to Johnson that Lopez not add bulk purely for the sake of adding bulk. "I want to see what you're doing in the weight room translate on the court," Johnson recalled telling Lopez. "I didn't see that when I first got here.…That's what we're hoping for, that what he did in the off-season will start translating more."

There were some positive signs in the preseason. In six games, Lopez averaged a team-leading 16.4 points and 7.4 rebounds. Johnson said he had a special statistical category for Lopez: attempted rebounds. Lopez said he could practically hear Johnson in his sleep: be aggressive, be aggressive, be aggressive.

Against the Raptors, Lopez showed some toughness. He was 8 of 17 from the field and wasn't afraid to draw contact. He also went 11 of 15 from the free-throw line. "He made some strong moves," Johnson said.

But rebounding, of course, was a different story. Lopez's total rebound rate against the Raptors was 9.8. Nets forward Reggie Evans, who grabbed 13 rebounds in 16 minutes, had a total rebound rate of 50—which, in fairness to Lopez, is absurd. It essentially means that Evans grabbed half the game's rebounds when he was on the court. The 6-foot-8 Evans could be a safety net for Lopez this season. Better yet, he could be a role model.

"He's just all over the place on defense," Johnson said, "and, as you see, he loves to rebound."

It isn't something that comes naturally to Lopez. The Nets can only hope he learns to love it.