Baynes has been one of the keys to Boston's Playoff run that sees them up 2-1 over the Cavaliers ahead of Game 4 in Cleveland on Monday night [EST], the Aussie's three-point shooting surprising everyone but Stevens and Baynes himself.
Having secured an NBA ring under Popovich at San Antonio in 2014, Baynes understands what it takes to win a Championship. Playing alongside Spurs greats Tim Duncan, Manu Ginobili and Tony Parker, the Australian says he learned how best to prepare and the importance of routine.
But it was Popovich who ran the show, and Baynes sees a lot of the veteran NBA mentor in the Celtics' Stevens.
"They're both great with the X's and O's," Baynes said of the similarities between Popovich and Stevens. "They've all figured out more than I've ever learned, so every chance I get and can see some things from them, I'm trying to learn as much as I can.
"Their composure throughout the game is pretty much second to none. No matter what's going on on the floor, they're so composed in how they are with the team and the message that that sends through to everyone and keeps everyone calm."
While Baynes is full of praise for Stevens, the Celtics coach is equally fond of the "leader" he has in the Australian big man. Signed on a one-year deal ahead of this season, Baynes has been a vital defensive cog in the Celtics' run to the Eastern Conference Finals.
He then started dropping threes. In fact, Baynes' three-point percentage sits at .524 for the postseason.
"When he first got here, in the fall, I was just shooting around with him one day," Stevens said of Baynes. "He's mostly in the mid-range, but he made 30 out of 32. Even I [sic] kinda didn't know he could shoot it like that. Then when you watch the arc of it and the touch, the corners are easy for him.
"Above the break he's transitioning too, but I think a lot of times with big guys who haven't shot threes before, the floodgates open when you see the ball go through the net once. It's just unique when you've never shot it before and you catch and shoot it.
"If you kind of rewind back to that Toronto game, when he made a couple, that was huge because now he feels comfortable catching it. He's done a good job in this series obviously. When he shoots it, we all feel like it's going in. He works hard at it. I believe in him."
Having outlasted the Cavs down the stretch in Games 1 and 2, the Celtics gave up a 15-point first-quarter lead in Game 3 and never recovered.
There's always some kind of adversity at this point of the season but having lifted the trophy with the Spurs in 2014, Baynes can offer some insights as the Celtics look to cap a remarkable season by advancing to the NBA Finals.
"A little bit here and there, but it's a different group than what I had back then as well," Baynes said when asked if he'd shared his Championship-winning experience with the Celtics squad. "We're adjusting and finding our own way. We understand now what it is to play Playoff basketball, but it keeps getting more intense every game.
"That's what these guys are seeing, and they've been able to adjust to it really well. It's something that, yeah, we're focused on as a target as a group, and we're not satisfied yet, that's for sure."