But while Monday's game provided a chance for a reunion with his former Butler teammate, Jazz swingman Gordon Hayward, Mack's focus has shifted.
"I talk to him a little bit. We're focusing on the NBA," he said. "Everybody's doing different things now. It's good to catch up with those guys and talk about the old times, but we've got different situations going on. We try to live in the moment."
For Mack, that means moving full time to point guard and taking on a bigger role with the Hawks. After spending his first three seasons in the league with Washington and Philadelphia, Mack's found a home in Atlanta, alongside former Jazzmen Paul Millsap, DeMarre Carroll and Kyle Korver.
He's having the best season of his career, averaging 7.7 points and 3.8 assists.
"My guy Shell," Hayward said. "He's found a great place in Atlanta and he's playing well. I'm happy for him [and] what he's done. Just extremely excited for him."
Timing is everything
There's never a good time for a turnover, but the Jazz's timing could hardly be worse of late.
Over the team's six-game road trip (during which the Jazz won just a single game), Utah turned the ball over 95 times leading to 141 points for its opponents, an average of 1.48 points per turnover.
"It's when the turnovers are happening," Utah coach Tyrone Corbin said. "You don't want them to happen first of all, but especially where they lead right into layups and transition 3-point shots because we can't get back."
The Hawks' self-proclaimed "Junkyard Dog," Carroll, credits the Jazz with reviving his career during his two seasons in Utah. But the forward used his relentless work ethic to get better in another game too: bowling. As he returned to Utah, Carroll said he considered calling for an impromptu bowling tournament in town but decided against it at the last minute.
"When I got in I was too tired," he said. "[And] my bowling skills aren't up to where they used to be right now because I've been in the gyms so much."