BOSTON -- It was late in Brad Stevens' first season with the Boston Celtics and the team was enduring a stretch in which it would win just one time in 15 tries while stumbling to the finish line of a 25-win season. After another win slipped away, a frustrated Stevens spotted Celtics legend Tommy Heinsohn in one of TD Garden's small, dimly lit changing rooms and plopped down next to him hoping for some words of wisdom.

"Tommy says, 'I have a great idea for you: When you get home, open up that computer then close that computer and go have a beer,'" Stevens recalled with a smile. "That was some of the best advice I got."

To most around Stevens' age (38), Heinsohn is best known as a referee-disdaining, green-pompom-waving caricature in his role as Celtics TV color commentator. Unfazed by hyperbole, Heinsohn compared undrafted 26-year-old rookie center Greg Stiemsma to his former teammate -- and 11-time NBA champion -- Bill Russell a few years back, leaving the entire viewing audience (and all of the Internet when the clip started circulating) slack jawed.

But that's TV Tommy. To Stevens and those steeped in the history of the Celtics organization, Heinsohn is the gold standard. He is Mr. Celtic.

A winner at every level, Heinsohn helped Russell to eight championships in nine seasons as a player, then raised two more banners in nine years as coach. In between, and ever since he hung up his whistle, Heinsohn has been a part of the team's TV broadcasts.

Essentially, he has been part of all 17 banners and is connected to just about every bit of the team's history.

But Heinsohn's coaching exploits are often a footnote to his biography. This despite the fact that his 427 coaching wins rank second in team history to Celtics patriarch Red Auerbach. Heinsohn posted a .619 winning percentage and was the NBA Coach of the Year for the 1972-73 season. He helped usher in small ball and jokes he's the "last oak tree" in regards to up-tempo basketball.

That resume is a big reason why Stevens cherishes those meetings with Heinsohn. Sometimes they provide much-needed levity, often they deliver a history lesson. But mostly, they are a chance to pick Heinsohn's encyclopedic brain about the game of basketball. Just two coaches talking about their vocation.

On Friday, Heinsohn will become only the fourth player in league history to enter the Basketball Hall of Fame as both a player and a coach when he's inducted as part of the Class of 2015 for his time on Boston's bench. He'll join a group of dual inductees that includes only Bill Sharman, John Wooden and Lenny Wilkens.

Tommy Heinsohn's 427 coaching wins rank second in Celtics history only to Red Auerbach. AP Photo

"What he did as a coach -- and he coached teams that sometimes were traditional, sometimes weren't -- and really had great success," Stevens said. "And then his impact as a player, and his impact in the community, and on TV. I'm just happy for him. I count myself fortunate that Tommy Heinsohn will just swing by my office."

And while it has been almost half a century since Heinsohn roamed the sidelines, Stevens' sentiment is one echoed by many of the Boston coaches that followed. Stevens and Rick Pitino actively sought Heinsohn's coaching advice, while Doc Rivers can't gush enough about what Heinsohn meant to him.

"Tommy was the absolute best," Rivers said. "Tommy was great, obviously, when we were winning, but, for me, Tommy was the best when we were losing -- those two or three years. He would see me sometimes and just come over and sit with me on the plane. He got it. He just kept telling me over and over, 'You're a really good coach. You're really good. You just need to hang in there.' ... I don't know how many times he told me that.

"And so when we started winning, it was really cool. The thing I still remember, when we won the title [in 2008], I looked over and Tommy was crying. And I was thinking: He's the true definition of what a Celtic is. And he's the best. Tommy means the world to me."

The Jersey-born Heinsohn landed with the Celtics as a territorial pick out of College of the Holy Cross in nearby Worcester, Massachusetts, where he had guided the Crusaders to the NIT championship in 1954. Thanks in part to Bill Russell's late-season arrival in 1956 -- the Melbourne Olympics and a gold medal beckoned the big man -- Heinsohn won the NBA Rookie of the Year honor after an All-Star season in which he helped Boston to its first title.

Playing alongside Russell and fellow Holy Cross product Bob Cousy, the 6-foot-7 Heinsohn knew he'd always be in the shadows. He likes to joke about a 42-point, 26-rebound effort against the Lakers during a game in Seattle in which his accolades were buried in the final paragraph in the next day's newspaper (Russell, the area native, and Cousy, the Houdini of the Hardwood, garnering the headlines and full-page spreads). Heinsohn figured he wouldn't be a star in the league, but pledged to cement his legacy in other ways.

And the Celtics wouldn't have hung eight title banners without Heinsohn. He can instantly recall his stat line -- 37 points, 23 rebounds -- when asked about his performance in Game 7 of the 1957 NBA Finals against the St. Louis Hawks. He proudly recalls never backing down when Auerbach told him to get in the way of Wilt Chamberlain.

"... when we started winning, it was really cool. The thing I still remember, when we won the title [in 2008], I looked over and Tommy was crying. And I was thinking: He's the true definition of what a Celtic is. And he's the best. Tommy means the world to me." Doc Rivers

Heinsohn, a six-time All-Star who averaged 18.6 points and 8.8 rebounds per game for his career, tore up his foot and retired from playing at age 30 after the 1964-65 season. When Auerbach hung up his whistle a season later, he asked Heinsohn to consider coaching, but Heinsohn advised him to hire Russell in the role of player/coach instead. Three years later, Auerbach finally got Heinsohn to take over on the bench when Russell retired.

During the break between his playing days and coaching, Heinsohn did two things: (1) He started broadcasting where he, ironically, often played the straight play-by-play man to Auerbach's homer analyst during early TV broadcasts, and (2) he headed a life insurance company.

Heinsohn was a Stevens-like 35 years old when he was elevated to head coach. Amid early struggles, some in the media suggested that Heinsohn ought to go back to the insurance business. Earning coach of the year in 1973 and winning a title a year later offered validation, but Heinsohn still reflects fondly on the insurance years.

"I'm glad that I had been in the insurance business because I found out how much of a genius Red Auerbach is. I took management training courses over the four years I was out and I learned a lot about the management principles," Heinsohn said. "When I got the [coaching] job, I figured I'm going to be dealing with people that are really very motivated. Unlike the life insurance business where you really have to motivate people until they caught on and really enjoyed it. Basketball players, by the time they get to the pro level, are very, very self-motivated. I was looking forward to having fun, and I had a game plan because I played for a great coach and knew the philosophy and the strategy and the tactics."

What was Heinsohn like to play for?

"I think if you ask Jo Jo [White, a fellow 2015 Hall of Fame inductee] what my favorite expression was, he'd tell you, "Go through!" Heinsohn said, his voice elevating to sonic boom as White, seated nearby, playfully rattled to attention. "Which means you better sprint from one end of the court to the other."

Confirms White: "You can bet that you will be ready to go because [Heinsohn] made sure we were ready to go. ... He actually shocked me [as a young coach]. I was in awe. Because every timeout, every game, every practice, Tommy was right on top of us to make sure we got the job done."

Heinsohn found success in the 1970s with teams that included John Havlicek and Dave Cowens. He implored his players to outrun their opponents and utilized Cowens in the unfamiliar point-center role. This year's Hall of Fame weekend, with White finally being inducted after a long wait, is a chance for those '70s teams -- the ones that fell between the much-beloved Russell and Larry Bird eras -- to get some deserved time in the spotlight.

Tommy Heinsohn averaged 18.6 points and 8.8 rebounds during his nine-year Hall of Fame career with the Celtics. Sportswire/AP Images

Heinsohn, elected as a player in 1986, was a finalist for the Hall as a coach in 2013 but didn't get voted in. The call from the veteran's committee to inform him they had directly elected him this year came as a surprise.

"It was totally unexpected, to tell you the truth, because I was on the ballot a few years ago and I got a phone call that said I didn't make it, but I had support," Heinsohn said. "I figured that was the end of that. All of a sudden, I got a phone call a few years later and the veterans committee elected me. I feel very honored to be in select company like John Wooden and my teammate Bill Sharman and one of our competitors in Lenny Wilkens."

Heinsohn downplays the suggestion that he has been around so long that no one quite understands how much he means to Celtics lore. Heinsohn loves the line often offered by Mike Gorman -- his TV sidekick and the other half of Boston's announcing tag-team champions since 1981 -- that goes a little something like this: There's a generation of fans that (barely) remember Heinsohn as a player; there's a generation of fans that remember Heinsohn as a coach; another generation that knows him as an announcer; and most kids think he's Shrek.

Heinsohn still unleashes his hearty ogre-like laugh when he hears the line. Because there's much truth to it. Despite all his success as a coach and a player, it might be Heinsohn's four-decade tour as an announcer that's most deserving of Hall of Fame status.

Just ask Rivers, who is still a frequent viewer of Celtics games.

"First of all, you still have to watch the games as long as Tommy is doing them because that's entertainment. You don't get that type of entertainment anywhere else," Rivers said.

Heinsohn has reduced his role in recent seasons, often appearing from Comcast SportsNet's Burlington, Massachusetts, studios during road games to limit his travel. Another generation of fans from other markets -- introduced to Heinsohn in large part thanks to NBA League Pass -- believe Heinsohn's homerisms are nauseating and don't understand he's simply following a well blazed trail left by Auerbach and especially longtime radio voice Johnny Most, who taught Heinsohn the commentating ropes.

Heinsohn's impact in the booth is impossible to deny. Walter McCarty, now an assistant coach on Stevens' staff, became a cult hero in these parts in large part because of the way Heinsohn would bellow, with perfect New England accent, "I love Waltah!" during broadcasts.

Rather than coach the Celtics himself, Heinsohn advised Red Auerbach to hire Bill Russell as player-coach in 1966. Brian Babineau/Getty Images

As the story goes, Heinsohn was so enthused by McCarty's grit, he would hype the forward after hustle plays by shouting, "I love Walter!" Cousy, a common broadcast presence back then, liked to play it straight, according to Heinsohn, but after McCarty hit a game-winning 3-pointer one night, Cousy professed on air that he, too, might be falling in love with McCarty's game.

Heinsohn pounced immediately and playfully revoked Cousy's membership in the McCarty Fan Club but suggested that viewers who desired to join could simply open their windows after each game and scream, "I LOVE WALTAH!" The station was flooded with letters from parents that wanted their children to stop screaming McCarty's name. Vendors still sell "I love Waltah!" shirts outside TD Garden.

It's easy to forget, too, that Heinsohn was a mainstay of CBS's playoff coverage in the 1980s and often had to stifle any opinions while calling Celtics-Lakers matchups in the NBA Finals alongside Dick Stockton. In those instances, Heinsohn insists that he simply tried to use his knowledge of the game to break down the matchups.

Heinsohn doesn't have to worry about that now. He can hand out "Tommy Points" to his scrappy favorites and compare rookies to Hall of Famers while knowing his audience is clinging to every word.

After all, everything Heinsohn says carries additional heft. That's why everyone -- viewers, players and even Stevens -- listen to everything he says.

And why wouldn't they? Heinsohn has seen it all. He has been a part of everything. His latest call to the Hall only confirms that Tommy Heinsohn is Mr. Celtic.