Marcus Smart got a key assist from Chauncey Billups this offseason

Marcus Smart made fitness an offseason priority.jim davis/globe staff file

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NEWPORT, R.I. — Each summer, Celtics assistant coaches crisscross the country to spend time with the players. They work on new skills, refine old ones, and simply strengthen bonds.

This offseason, Jay Larranaga was assigned to work once again with tenacious fourth-year guard Marcus Smart. And Larranaga decided that in addition to the usual instruction he offered, it would be good to have someone to complement it.

“I think role models are always really important,” Larranaga said. “And as Marcus and I have worked more and more together, you start to break down all the different parts of Marcus as a person — physically, athletically, career path, all those different things.”

Larranaga noticed similarities between Smart and retired seven-time All-Star Chauncey Billups. So he contacted former Celtics assistant and current Cavaliers head coach Tyronn Lue, who is one of Billups’s closest friends, and asked if Billups might be open to meeting with Smart. Billups responded almost immediately.

“He said he was already a big fan of Marcus’s, but also thought there were things in his game he could refine, and maybe had some experience and knowledge he could pass on that would be helpful,” Larranaga said.

“I just thought it was a great role model for Marcus. Even their style of play as physical guards that are really good in pick-and-rolls, really good at hitting the open man and just making all their teammates better, it just seemed to make sense.”

Billups invited Smart and Larranaga to visit him in Denver, and in late August they flew out to spend three days there. Like Smart, Billups started his career searching a bit for his position. He was a relentless defender whose point guard skills were somewhat crude, but he learned important lessons from veteran floor general Terrell Brandon.

Smart and Billups completed on-court workouts at the University of Denver, watched film, and simply talked about the game’s various nuances. Billups’s knee was a bit sore from playing in the BIG3 three-on-three tournament, so he and Smart were not able to lock horns, although there still may be a time for that.

“It was tremendous,” Smart said of the visit. “Me and Chauncey are similar in a lot of ways. We’re bigger guards who like to impose our will, who love contact. So being able to learn from a guy who knows what it takes to play in this league a very long time and win a championship, to learn and kind of pick his brain was good.”

Billups was a below-average shooter who ultimately turned into one of the game’s more accomplished marksmen. He made 33.1 percent of his 3-pointers over his first three seasons, but went on to shoot better than 40 percent five times, including twice finishing among the league’s top eight shooters.

Smart has made just 29.1 percent of his threes over his first three years, so Billups’s story offers hope.

On the court, Billups showed Smart simple things, like new and creative ways to find openings for his shot. But Smart found Billups’s advice about preparation most useful.

“Just becoming more of a professional and working smarter, and doing things to help in the long run,” Smart said. “Just getting a routine down, keeping that routine and finding what works for you. Keeping it short and sweet to get to the stuff you’re going to do in the game.”

Larranaga said that Smart began to invest in the preparation needed to become great. He has always played hard and been a ruthless competitor, Larranaga said, but he understands that to become elite, it will take more than that.

“Champions put a lot of time and effort into preparation,” Larranaga said. “They take care of their bodies, they work on their skill, how they get treatment. They’re healthy and live a really healthy lifestyle and continue to work on the areas they need to get better at. So I think he’s really doing that right now.”

Smart’s new, trim physique has been noticeable at Celtics training camp. He said that after last season, even before president of basketball operations Danny Ainge suggested he lose some weight, he had already begun crafting a plan to do exactly that. By switching to a more Mediterranean-centric diet and revamping his sleep patterns, Smart lost nearly 20 pounds.

Larranaga said the changes are already showing value, but he believes Smart is still two years away from reaching his full potential.

“When I see Marcus, I see a guy that’s going to be a very good 3-point shooter, a very good pick-and-roll player and an elite defender,” Larranaga said. “I think his shot and decision-making are going to continue to get better and better, and his defense, especially being lighter and quicker, is going to get better and better.”

Smart is eager to chase those goals, and he is hopeful that Billups will remain his mentor along the way. The two have continued to exchange text messages since their August boot camp in Colorado, and Smart said he intends to reach out to Billups after games this season to pick his brain.

“I definitely feel like it’s going to be a special relationship,” Smart said.