The Blazers forward could use his size and strength to earn minutes early. (1:12)

LAS VEGAS -- Caleb Swanigan was on the wrong side of the basket when a teammate missed a free throw that caromed to the opposite side, moving away from him.

The odds were against Swanigan chasing down the offensive rebound. And yet two San Antonio Spurs barely blocked out the Portland Trail Blazers rookie from squeezing between them and beating them to it.

A first-round pick (26th overall) out of Purdue and a double-double machine, Swanigan arrived to the Las Vegas Summer League with Big Ten Player of the Year credentials and a reputation as one of college basketball's best players last season.

But the way Swanigan chased rebounds on Tuesday, constantly moving his feet and trying to navigate through bodies in the paint with his hands as if he were engaged in hand-to-hand combat, the 6-foot-9 rookie played like a journeyman trying to make the most of his final shot at earning a roster spot in the NBA.

"My motor is going to be the best in the NBA," Swanigan said. "That is my goal, that is what I want to be. You come watch Swanigan play, he is playing hard every night, just talking, just trying to win. That is the type of player I want to be and the legacy I want to leave."

Swanigan looks like he is a man on a mission, here to outwork every big on the glass in Las Vegas. He collected his second double-double in three games with 19 points and 13 rebounds in a 99-85 loss to San Antonio on Tuesday. It was his second time grabbing 13 rebounds in summer league play.

Through three games, Swanigan is averaging 15.6 points and 11 rebounds while snatching a total of 12 offensive rebounds. Swanigan tries to make up for his lack of elite athleticism with effort and footwork under the rim.

In fact, Swanigan often hears how he reminds people of another former Trail Blazer who wore No. 50 and came from the state of Indiana.

Caleb Swanigan, the second of two Portland first-round picks in the 2017 NBA draft, will attempt to establish himself among a crowded Trail Blazers frontcourt. Noah Graham/NBAE/Getty

Swanigan's under-the-rim game with a soft touch, complete with a gritty lunch-pail mentality, reminds some of Zach Randolph.

"I think you can probably see some similarities," Portland coach Terry Stotts said. "Zach has obviously improved his game but over the years it has kind of changed a little bit. But I think that would be a fair comparison."

Like Randolph, Swanigan has had plenty of obstacles to overcome. Growing up in an unstable housing situation that saw him bounced between Indiana and Utah, Swanigan watched his mother, Tanya, raise six children.

His father, Carl Swanigan Sr., battled drug addiction and weighed close to 500 pounds when he died at age 50 due to complications from diabetes and years of drug abuse.

Swanigan struggled with his own weight, once weighing as much as 360 pounds the summer before eighth grade. But he transformed his body in high school and during his two years at Purdue.

He was in the best shape of his life during his draft workouts, and the Blazers have been pleased with his conditioning so far.

"He is in great shape, the guy works really hard," Stotts said. "He was coming in early and getting extra cardio in, he is really committed to being a well-conditioned athlete. With his background, he knows the commitment that it takes."

Swanigan says that eating healthy and staying disciplined has become so ingrained in him that he has not had to hire a nutritionist or personal chef.

"Nah, it's simple," Swanigan said. "Just eat right. Eat right and workout. Just got to keep it simple. There is no trick to it."

There also is no disguising his secret to success thus far. Swanigan just plans on outworking everybody on the glass.

"What makes him an elite rebounder is his desire to go after every rebound," said Blazers summer league coach Jim Moran. "As a coaching staff we love seeing that. He doesn't give up on any plays and is always going after every ball, and it paid off a couple of times."

Swanigan has his work cut out for him in Portland, where the Blazers have several bigs, including Zach Collins, the 10th overall pick out of Gonzaga.

Swanigan, though, has been working on adding a 3-point shot to stretch the floor. He has knocked down two 3-pointers so far in Vegas.

"You know what? He has already shown it," Stotts said of Swanigan's outside shot. "He has worked on it ... He shot the college 3 well, I think he will have the ability to move out."

"He hasn't shown any reluctance to step into them," Stotts added. "We will see how it goes. People know me ... I don't discourage 3s."

Swanigan has run into Randolph before since they are Indiana products. He has taken the advice Randolph has given him to heart.

"Just be a dog," Swanigan said of what Randolph told him. "Come out here and fight. Fight every night."

"I like what Z-Bo does, the dog in him," Swanigan added. "And it is every night for Z-Bo, you come out, you know what you are getting from him. And that is what I like about him and that is the part of his game I try to put in mine."