SOUTH PORTLAND — Jon Jennings stands at midcourt in Beal Gymnasium, watching intently as the South Portland High boys’ basketball team runs through a 4-on-3 drill at practice.

Jennings doesn’t say a word, but when the drill is over he pulls aside junior guard Alex Bambile. They talk briefly and practice resumes. “I was just talking to him about recovery,” said Jennings. “He was sunk so far into the paint that he was unable to recover to (defend) the shot.”

It was just a little tip, but exactly the kind that the 57-year-old Jennings is dispensing these days to the undefeated Red Riots in his role as a volunteer assistant coach.

“He’s always in my ear, telling me to focus, to go hard,” said senior guard Cade Carr.

Jennings is better known as Portland’s city manager, overseeing more than 1,400 public employees and a municipal budget of more than $200 million. But this winter, for the first time since 2012, Jennings is once again playing a role in a sport that has been a part of his life since he was a child in Richmond, Indiana.

“I’m having so much fun,” he said. “It’s reinvigorated me in so many ways.

“It’s a good diversion for me. You deal with a lot of things in my full-time job and, as I’ve said my entire adult life, any day spent inside of a gym is a good day.”

Jennings, who sometimes misses practice because of his duties as city manager, brings a resumé that is probably unmatched by any high school volunteer coach in the nation.

He began his basketball apprenticeship under legendary coach Bob Knight, serving as a student-manager at Indiana University. While attending college, he got a job with the NBA’s Indiana Pacers as a scout and video coordinator. For 11 years, beginning in 1986, he worked with the Boston Celtics, including four years as a scout, four years as a bench coach, learning the game from the likes of Red Auerbach and K.C. Jones, working with stars such as Larry Bird, Kevin McHale and Reggie Lewis. After that, he held a variety of positions in the Clinton administration, and then the U.S. Department of Justice.

And, of course, he helped to bring professional basketball’s Maine Red Claws to Portland, serving as president and general manager for the team’s first three years, through the 2011-12 season.

Jennings contacted South Portland High athletic director Todd Livingston last summer to ask about coaching in high school. Livingston suggested Jennings meet with Kevin Millington, the Riots head coach. And once they met, Jennings had a spot on the team’s bench.

“Obviously he’s got an incredible story, and not just related to basketball,” said Millington. “He seemed like a good fit for us. And he’s got this incredible passion for basketball which he’s now bringing to the kids.”

Jennings was itching to get back into the sport.

“I love the game of basketball and I missed being in the gym and teaching the game,” said Jennings, who is thankful for the support he has received from Portland officials on his new venture. “All these years I’ve been in Maine, I’ve really missed coaching, being around the players. That’s the reason I wanted to do this. I absolutely jumped at the opportunity to learn the high school game. … And I’ve been very fortunate to be learning the high school game from an incredible coaching staff.”

Everything, said Jennings, is relative. The South Portland players obviously aren’t as talented as those he coached in the past, but that’s what he loves about them.

“The game is different from the NBA or the college level,” said Jennings. “But it’s still a round ball and there’s still two hoops and there’s 84 feet instead of 94. I can’t tell you how much I’m loving being part of the team and contributing in a small way.”

Yes, he talks to the players sometimes about his days with the Celtics, but doesn’t dwell on it. “He’s pretty humble about it,” said senior Hunter Owen.

Besides, Jennings said, many of the Riots don’t know the NBA players from the 1980s. Jennings said he earlier told the 6-foot-5 Owen, who is receiving a scholarship from Vanderbilt to play baseball, that he wanted him to hold the ball up high after getting a rebound so no one could steal it. “Like Kevin McHale used to do,” added Jennings.

Owen recognized the name, but didn’t know exactly who McHale was. Senior guard Geremi Baez said Jennings recently compared one of the Riots (Pamba Pamba) to the late Reggie Lewis, in terms of having the same slashing style to the basket. “I didn’t know who (Lewis) was until I searched him later that night,” said Baez.

But the players don’t expect stories from Jennings, although Cade said he sometimes shares them in the parking lot after practices. They are looking for direction.

“Just to have him on our bench, the experience he has, he’s a book of knowledge,” said Baez. “We take advantage of that, we ask him as many questions as we can.”

Baez credits Jennings with pushing him to become better: “He kind of brought my confidence up at the beginning of the season.”

Jennings doesn’t want to talk too much in his role, and when he does it’s usually about defense or the mental approach to basketball. “This is Kevin’s team,” he said. “It’s his voice the team needs to hear.”

But Millington said Jennings has begun to offer more input as the season has progressed. In a recent game, the Riots were struggling to get the tempo in their favor. “We like to play fast,” said Millington.

So Jennings suggested going to a full-court press, something the Riots rarely do. “Just to get the game faster,” said Millington. And South Portland responded with an 18-2 run to break the game open.

Millington calls Jennings an “old-school coach.” And that’s good. “The last time he was coaching, the game was different,” said Millington. “And it’s good for me to talk to him about that, and the roots of basketball, and how they’re connected.”

The game, Millington said, is more guard-oriented now. Jennings reminds him to get the ball inside to players like Owen – who reminds Jennings of McHale and Danny Ainge in his playful attitude – to keep the team balanced.

“He brings a lot of positive energy about basketball,” said Millington.

Jennings, whose daughter Abby plays basketball and field hockey as a sophomore at Cheverus High, said he has had some friends ask whether coaching high school players was a step down given his extensive experience.

“Absolutely not,” he said. “This is the beauty of the game, at the high school level. These are young men and women who are desperately learning the game and wanting to learn the game and not getting paid to learn the game. That’s very exciting to me.”

Jennings would like to be a high school head coach some day. After all, he said he has a little experience with successful programs. For now, though, he’s learning as much as he can.

“Right now I’m having the time of my life,” he said. “I feel like a kid again.”