The physical transformation of Patty Mills was so dramatic one could be excused for wondering if the San Antonio Spurs had signed a new point guard in the offseason.

Gone was the somewhat doughy physique that jiggled when Mills sprang from the Spurs’ bench, madly waving towels to punctuate a basket by one of his teammates.

A healthier diet and improved conditioning has done more than transform Mills’ physique. It has turned him from someone who led choreographed cheers from the bench to a key reserve that creates chaos on the floor with his long-range shooting and pestering defence.

“He’s a really committed player,” San Antonio coach Gregg Popovich said. “He came in this year with a changed body that he worked on all summer. Mentally he’s been making great decisions. He’s been a significant factor for us all season.”

Mills helped the Spurs earn the league’s best record, and the Australian’s emergence could be even bigger now that Tony Parker is dealing with an ailing left hamstring.

When Parker left game five against Portland in the second quarter, Mills responded with 18 points, three steals, three rebounds and two assists in 26 minutes as the Spurs rolled to a 104-82 victory to close the series.

“He is very aggressive,” teammate Boris Diaw said. “At the same time, he had to be a leader and he had to be under control like Tony does. He did it tonight.”

Parker sat out 14 games this season, including two weeks for what Popovich deemed “rest”. The Spurs were 11-3 without their All-Star point guard, and Mills’ presence was a big reason behind that success. He averaged 10.2 points and 1.8 assists in a career-high 18.9 minutes per game.

“It was huge, it was huge,” Parker said of Mills’ development. “Patty’s played great this year. He had a hard time the first couple of years to try to find a spot, but this year he came in and he was ready.”

Popovich made no bones about what was keeping Mills from being a viable option in his previous two seasons with the Spurs.

“He was a little fat ass,” Popovich said. “He had too much junk in the trunk. His decision making wasn’t great, and he wasn’t in great shape. He changed his entire body. He came back svelte and cut and understood you have to make better decisions, point-guard type decisions. He did all those things better and he earned it.”

While the 183cm Mills is still listed at 84 kilograms as he was last season, he is much more trim and toned. It’s earned him some playful teasing from teammates that he rarely wears a shirt around the locker room anymore.

“My fitness base has given me the ability to play stronger for a longer period of time. It’s definitely helped for sure, I’m glad I did it,” he said.

After averaging 5.1 points in 11.3 minutes during San Antonio’s run to the NBA Finals last year, Mills quickly emerged as the team’s primary backup at point guard this season after entering the year behind Cory Joseph and Nando De Colo on the depth chart.

“It’s just understanding my role on the team and understanding where you can get shots in the offence and do stuff defensively that I didn’t really understand before,” Mills said.

More so than his offence, Mills’ determination on defence has led to the increased role with the team. His pestering presence from the moment the ball is inbounded resulted in 79 steals this season, including 11 in 12 postseason games.

Mills’ emergence has also allowed Parker to enjoy his time on the bench, transforming the team’s spirited guard into a raucous cheerleader at times. When Mills hit a key basket late in a regular-season victory over the Trail Blazers, it was Parker who sprung from the bench waving a towel in celebration.

“No, he didn’t, no he didn’t,” Mills said. “I wish I had seen that. I need to see some footage.”