But before the illusions of a Tatum return to the Celtics and perhaps a deep playoff run, Smith’s story of recovery and perseverance is worth noting. He was waived or released five times by the Heat before earning a two-way contract several months after tearing his ACL. He was a few months into that deal before a second catastrophic injury.

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The comeback from two major leg injuries was arduous.

“It’s slow, it’s tough, boring some days but it’s kind of a process,” Smith said. “You have to take it day by day and always see how your body is responding.

“I think everybody goes through it their own way. It’s different for everybody. You have to make sure to listen to your body, understand how its responding and make sure it’s not too tentative. If your body is telling you to keep going, then keep pushing.”

Smith was determined to vigorously rehabilitate but not skip any steps. Recovery from an Achilles injury is one of the more tedious courses for a high-level athlete. But as the summer approached and Smith continued to pass team-mandated tests, training camp became a strong possibility.

“I think by camp I was able to feel pretty good, so eight or nine months,” Smith said. “It’s different than you think. You have a few negative thoughts in the back of your mind but you just have to understand you put in the work to get back to that point.

“I think once you get out there a couple of times and you realize you’re fine, you’re gonna be OK and you start to have confidence in the work that you put in. The first couple of times you get out there it’s a little difficult, but after that you get back to playing basketball.”

Miami coach Erik Spoelstra said the team couldn’t get rid of Smith. He kept returning after being waived, which was just as impressive as his injury recovery. His admiration for Smith’s diligence was obvious.

“He has a super power of resilience, he really does,” Spoelstra said. “I’m not even sure if you can coach it, teach it, drive it. I think because of how his journey and how he got here, he just would not take no as an answer. He had doors shut on him more than he had doors open to him, and most players quit. We’ve cut him more times than I can count — probably seven, eight, nine times — and he just kept on coming back.

“We wanted to invest our resources and our staff to him even before he got hurt but sometimes the business, you have to make moves and he just stayed with it and so it makes us want to work even harder for him. So his resilience is incredible to come back from the injuries as just as impressive as he’s come back from doors being shut on him.”

Celtics coach Joe Mazzulla has mostly stayed out of the Tatum rehabilitation discussion. He has left that to Tatum’s medical team and team management. The Heat told Smith to be patient in his training, but the message did not always resonate.

“The whole process with him was trying to slow him down,” Spoelstra said. “You love it with guys like that; he’s always pushing the envelope. He kept on telling everybody he’s going to be ready for training camp. We told him to take your time, we want to be responsible about this, but he passed every check mark during the summer and he kept on pushing for more. He was available in training camp. That’s the kind of fortitude he forces upon you.”

The NBA has been littered with players suffering Achilles injuries over the past few years, with Kevin Durant, Dejounte Murray, Damian Lillard, and Tyrese Haliburton joining Tatum in sustaining tears. Decades ago it was considered a career-altering injury, but advancements in surgical technology and rehab procedures have turned recovery into less than 12 months.

Smith said he maintained privacy during his sojourn.

“I didn’t really reach out to anybody,” he said. “I was in a bad spot there for a second because I was coming off the ACL and then played for about three months and went straight to the Achilles rehab. I just kind of kept my head down there for a while, just trying to wrap my head around what I was about to go through again. I put a lot of trust in our medical staff. I knew that, as long as we worked together and stayed on the schedule, I can get back to being myself.”

Dru Smith was at TD Garden under Heat coach Erik Spoelstra’s watch, chasing after the Celtics’ Jaylen Brown.Matthew J. Lee/Globe Staff

Smith said he tried to block out the Achilles injuries to Lillard, Tatum, and Haliburton, all of which occurred in a two-month span.

“It just got harder and harder to watch more and more guys go down and thinking back to those first couple of months,” he said. “At that point I was a few months in, so I was walking. But it took me right back to that moment when it was all taken away and you’re just trying to figure out what’s next. Definitely tough and it’s just a tough rehab and now you have to go through it.”

The Smith story is a success story. At age 27, he has returned to the world’s best league despite two major injuries in the past 24 months.

“What kept me motivated was wanting to get back to playing,” he said. “I didn’t want that to be the end of my story because an ACL and Achilles is not really getting to see what (my story) looks like. I did have thoughts initially of ‘why me?’ I had to shut my mouth. You feel for whatever reason this is part of your story and don’t really get a chance to ask why me, you have to put the time and put the work in and get back to yourself.”

PASSING GRADE

Cunningham, Pistons welcome being tested

The Pistons came into TD Garden two weeks ago and eked out a close win in their third tight game against the Celtics this season, and superstar Cade Cunningham, one of the league’s rising scorers, had nothing but admiration for the former champions.

“They’re a championship team, play with championship identity,” he said. “Play a great brand of basketball so it’s always a test for us coming in. It’s a game we love coming in for because we know they’re going to test us and play good basketball.”

The Pistons have raced to the No. 1 seed in the Eastern Conference by being as effective on the road (11-4) as at home (12-2). But the franchise is two years removed from a club-record 28-game losing streak, something Cunningham, Jalen Duren, and Isaiah Stewart won’t forget despite their ascension.

“I always remember where we’ve been and carry that with us where we go,” Cunningham said, “We don’t get too high because of where we’ve been, at the bottom level. We’ve been where we were searching for answers. Never got too low because we knew it could turn around.

“We have all the talent in the room we need to get the job done. We have a great group. We have a lot of guys that have been through a lot, even with Tobias [Harris], Duncan [Robinson]. Those are guys who have faced adversity and came out on top of it. I think that’s something that this locker room has in common, all of us. We can bond over that and it’s made us a close-knit group and we’re winning games because of it.”

NEW VOICE

Carlisle handing off union lead to Bickerstaff

This reporter’s question to Rick Carlisle on K.C. Jones’s Hall of Fame coaching chances prior to the Pacers-Celtics game on Dec. 22 turned into a surprise announcement that impacted all NBA coaches.

Carlisle, the president of the NBA Coaches Association, dropped the nugget that he was stepping down from his post, to be succeeded by the Pistons’ JB Bickerstaff. For the past two decades, Carlisle served as a spokesman for league head coaches, often lamenting the firing of his brethren and detailing the difficulties of the coaching profession. Carlisle, 66, has coached in the NBA for 24 seasons, won a championship with the 2010-11 Mavericks and willed the Pacers to the Finals last season. He is considered one of the league’s top strategists.

He said it was time for a fresh voice and lauded the 46-year-old Bickerstaff.

“JB is not only a trusted friend of mine and many, many coaches,” Carlisle said. “He’s a guy who’s proven to be a great leader in every place that he’s been. He’s had to take over difficult situations in his career, interim coaching positions. The job he did in Cleveland, taking that team from the lottery to winning in the playoffs was phenomenal. What he’s done in Detroit the last year and a half speaks for itself. He’s a great leader. He’s a passionate guy for coaches.”

For years Carlisle has presented the Chuck Daly Lifetime Achievement Award to the likes of former Celtics coaches Bill Fitch and Tom Heinsohn as well as Bernie Bickerstaff, the father of JB.

“Bernie was a very underrated coach and one of the first African-American presidents of an NBA organization,” Carlisle said. “We’re behind the scenes trying to help Bernie be recognized by the Hall of Fame as a contributor. There’s so many ways he’s influenced the game, both from the managerial side, the coaching side, and the silent mentorship that’s going on for decades with a guy like him. His lessons have rubbed off very well on his son JB. It will be a life-changing experience for him. It has been for me for two decades.”

As for Jones, his Hall of Fame case has been a source of debate and mystery for the past several years. He won two NBA championships with the Celtics and reached the NBA Finals three other times with the Celtics (1985, ’87) and Washington Bullets (’75). Jones coached only 10½ seasons, but he averaged 53 wins per year with a sparkling .643 winning percentage. He has already been inducted into the Hall as a player but his exclusion as a coach is curious.

There is a perception that college coaches have a much easier path to Springfield than their NBA counterparts. The likes of Bo Ryan, Gene Keady, Bob Huggins, Eddie Sutton, Lefty Drizzell, and Gary Williams have been inducted without a Division 1 national championship while Jones remains left out.

An encouraging sign recently are the inductions of Fitch, George Karl, and Rick Adelman in recent years.

“A guy that’s obviously very, very deserving,” Carlisle said. “I would think he’s got to be right there on the list. [The NBA coaches’ slight] has changed some in recent years. There were a lot of very important conversations with [Naismith Hall chairman] Jerry Colangelo and a lot of progress has been made. You see an NBA coach going in almost every year and that was not the case for a long time.

“And the difference between the college thing and the NBA thing, I believe is a thing of the past. I believe the Hall now has it right. Guys like [Dick] Motta, guys like K.C. Jones, who are right there, are going to have a chance — so it’s important that [the media] continue to get the word out, too.”

Motta, who led the Bullets to the 1978 NBA championship, is on the ballot as a coach this year along with former Celtics coach Doc Rivers. As for college coaches, Rick Barnes, Mark Few, Gene Bartow, Bruce Pearl, and Kelvin Sampson are all candidates.

Bernie Bickerstaff, Mike Fratello, Mike D’Antoni, and Gene Shue are candidates as contributors.

Rockets coach Ime Udoka’s bank balance dropped by $25,000 after a fine for criticizing NBA officials.Matthew J. Lee/Globe Staff

There are definite issues that need to be addressed between NBA coaches and officials after a difficult week where a handful of coaches not only called out what they felt was poor officiating but questioned the talent of the crews. Former Celtics coach Ime Udoka received a $25,000 fine for calling out two officials, including the highly regarded Zach Zarba, after his Rockets lost to the Nuggets in overtime. Udoka said that two officials “had no business being out there” and that Zarba was “starstruck.” The Timberwolves’ Chris Finch was ejected in a home game against the Thunder and fined $35,000 for his actions. Nuggets coach David Adelman also received a $35,000 fine for his harsh words toward officials in another overtime game against the Rockets, this one a Denver loss. That’s three coaches fined nearly $100,000 in one week. There has privately been an issue with officiating over the past few years, especially with the influx of new officials. Several veteran officials who garnered the respect of coaches and players have retired, replaced by youthful but sometimes sensitive and emotional replacements … Speaking of veteran officials, Eric Lewis has been reinstated to the G-League after being dismissed from the NBA for having a burner social media account. Lewis worked college games the past few years before applying for reinstatement … The Pacers added former No. 2 overall pick James Wiseman on a 10-day hardship contract after he was waived last season following an Achilles tear. The Pacers have been besieged with injuries and are thin at center, and that depth took another hit when Isaiah Jackson left the Dec. 22 loss to the Celtics with a potential concussion after being hit by an inadvertent Neemias Queta elbow. But Wiseman had his 10-day contract expire Friday and became a free agent again … Inasmuch as we lamented the ending of NBA basketball coverage on TNT, the public is responding positively to the ESPN, Amazon, and Peacock networks. The NBA reported that league ratings after two months are the highest in 15 years and an 89 percent increase from last season. There could be several factors, including the unique coverage by Amazon and Peacock, which includes a former player reporting from behind each bench. Peacock games are also carried by NBC on weeknights, which is a first for the network. NBC telecast regular-season games on weekends during their previous stint.

Gary Washburn is a Globe columnist. He can be reached at gary.washburn@globe.com. Follow him @GwashburnGlobe.