Forward Justin Jackson averaged 10.8 points, 6.0 rebounds and made 43.8 percent of his three-pointers as a freshman. (Katherine Frey/The Washington Post)

Justin Jackson sacrificed his body for the umpteenth time near the end of Wednesday night’s Maryland basketball practice. Coaches, teammates and scouts have all been demanding more consistent effort from the sophomore forward — so he threw himself into traffic during a long rebound and collided violently with several other Terrapins players. The entire gym stopped for a moment as Jackson hit the floor with a loud thud.

The new face of the program popped back up quickly and smiled before dishing out a no-look pass on the next possession. That combination of grit and flash didn’t come often enough during an otherwise promising freshman season, in which the 6-foot-7 Jackson — who sports a 7-3 wingspan and remarkable, 9.5-inch-long hands — introduced himself as an enticing NBA prospect but never put together a full body of work.

One week, he was hitting all five of his three-pointers and dropping 28 points on the road against Minnesota; the next, he was disappearing, such as in a Big Ten tournament loss to Northwestern, when he posted two points and three rebounds in 31 minutes.

It wasn’t until Jackson returned to College Park in the spring after attending the NBA draft combine that his coaches and teammates noticed a player who was ready to leave his struggles as a freshman in the past.

“I’ve learned a lot. The main thing I’ve gained is confidence,” Jackson said.

Jackson flirted with leaving school for the draft, but the consensus across the league was simple: For all of the physical tools that have made scouts drool, he not only needed to improve his athleticism and physicality, but he also needed to prove he could put it all together over an entire college season. He had heard those critiques from his own camp and from Maryland Coach Mark Turgeon. But the harsh evaluation and tough competition at the combine helped Jackson sharpen his focus before his sophomore season, which begins Friday night on Long Island against Stony Brook.

“We got a totally new Justin Jackson from the one that first got here,” said Kyle Tarp, Maryland’s director of basketball performance.

The Jackson who arrived in Maryland from his home town of Toronto was supremely talented and one of the most gifted athletes Tarp had ever worked with. Yet Jackson had little experience with weight training and couldn’t make it through the first conditioning warmup that Tarp put new players through. Jackson was expected to start and to carry the load as a power forward instead of his natural spot at small forward, yet he typically didn’t work out in the same group as the veteran starters because he was still adapting to his body and the grueling conditioning program.

“It was just learning how to work hard every day and push himself,” Turgeon said.

Jackson, Kevin Huerter and Anthony Cowan Jr. became the first freshman trio to start multiple games at Maryland in the modern era, and each logged at least 28 minutes per game. They faced constant questions about wearing down — especially Jackson, whose production was among the best for a rookie in the Big Ten: 10.5 points, 6.0 rebounds and a 43.8 percent rate on three-pointers.

Yet he scored in double figures in just three of his final nine games and looked gassed for much of the season’s final month — such as at Wisconsin in late February, when he scored six points on 1-for-5 shooting and finished with five rebounds. Turgeon pulled him late in the 71-60 loss for a lack of rebounding.

The Terps lost five of their final seven games to finish last season 24-9 overall and 12-6 in the Big Ten, with a defeat to No. 11 seed Xavier in the first round of the NCAA tournament ending their year.

“I will admit there were a few times where we hit a wall during the season. But we’re sophomores now. We’re grown. We’re ready. We’re more mature,” Jackson said. “So we know how to handle our bodies. We just know how to prepare ourselves for such a long season. It’s a grind.”

When Jackson returned from the combine, he sat down with Tarp to map out a new plan for his sophomore season. They targeted Jackson’s standing vertical jump — which measured 26.5 inches at the combine, the second lowest of the small forwards who attended — and worked on his trunk strength to help Jackson become more effective on the boards, an area of focus for a team that ranked 11th in the Big Ten in rebounding margin a year ago. By the end of the summer, Jackson not only could finish Tarp’s workouts with ease, but he was leading them as a veteran.

“My challenge to him was, ‘Hey, our big goal is for you to be consistent. You need to be the Justin Jackson that drops 28 on the road at Minnesota, every day. You can’t be the guy, 28 one day and only score six the next day. We need you to be a steady force for us all year long,’ ” Tarp said.

While Jackson played nearly three-quarters of his minutes at power forward last year out of necessity, Turgeon often relied on him to be the tank on the interior and surrounded him with four perimeter players. That will change this year: Jackson will play multiple positions and will be counted on as a centerpiece on the perimeter.

He will have the ability to start games at small forward and finish them as a stretch-four when Turgeon chooses to play small ball.

“We’re going to use Justin a little bit differently than we did last year, the ball being in his hands hopefully a little bit more,” Turgeon said.

That this is perhaps the most versatile team of Turgeon’s seven-year tenure in College Park is only true because of Jackson’s natural ability and the improvements he made to his game after his experience at the draft combine. There is little doubt that Jackson will leave for the NBA after this season; most analysts have pegged him as a first-round pick in next year’s draft.

Jackson has not addressed his plans, but in the offseason he often spoke of his new mentality.

“I’m just gaining confidence,” he said, “knowing I can go out there and be the player that I know I can truly be.”