It was late November, a couple of days after Orlando Magic coach Frank Vogel had gushed about Horford during his team's visit to Boston, dubbing Horford the "most underrated guy in the league."
Vogel's adulation was just the latest instance in a recurring series in which opposing coaches and players, often unprompted and without former ties to Horford, shower him with their loftiest praise. And now, after Boston's off-day workout, Horford is asked whether there was someone in the NBA who actually doesn't like him.
"Oh, I'm sure there's definitely people that don't like me," Horford said. But after pondering the query a bit longer, he apologized for not being able to pinpoint one such instance.
A pledge to uncover a Horford detractor was quickly deemed a fruitless pursuit by Celtics teammate Jaylen Brown.
"You probably won't find anybody," said Brown, who emerged with an even greater appreciation for Horford after spending part of the summer working out together near Atlanta.
"It doesn't surprise me at all [that everyone raves about Horford]. The way Al handles himself, both on the court and off, it's clean-cut, professional and high class."
On Tuesday night, Horford was voted an All-Star reserve by Eastern Conference coaches. His fifth All-Star bid was never really in doubt and you could make a case that, as Horford puts up some of the most efficient numbers of his 11-year career for the East-leading Celtics, he deserved at least some consideration for a starting spot in the frontcourt.
But the nod from the coaches is yet another reminder of just how much those closest to the game appreciate what Horford does.
"Al is just what every coach and what every player wants," Celtics president of basketball operations Danny Ainge said. "He's not going to fill up your fantasy sheet and all that kind of stuff. But he's who every coach and every player wants on their team. That says a lot."
That respect is essentially why no one can truly suggest that they dislike Horford. Even the big men he routinely spars with on the court offer nothing but praise. Sixers big man Joel Embiid, voted a starter in the East, said last week that he loves watching Horford and competing against him.
It seems it's hard to dislike somebody when you appreciate the way they carry themselves and the results they've produced.
"The only two people in the world that everyone seems to like are Brad Stevens and Al Horford," Celtics director of player personnel Austin Ainge said. "Capable people who are humble and not fake are very likable."
Grand Ledge (Michigan) boys' basketball coach Tony Sweet never quite got used to the sight of his 6-foot-8 star player dribbling the ball up the court. And he often reminded a teenage Horford.
"Once in a while he'd try to bring the ball up and I'd scream, 'Hey kid, give it to the guard and get under the basket. You score the points,'" Sweet said this week with a laugh.
Sweet had never coached a pure big like Horford and the two would often make the 20-minute trek to East Lansing to watch Michigan State games. Sweet remembers taking notes on the post moves that Big Ten big men practiced before games so that Horford could do the same in his workouts.
Fifteen years later, the Celtics routinely funnel their offense through Horford, who is maybe the poster child for the evolution of NBA big men. Horford is allowed to showcase his passing skills and Stevens encourages him to push the ball up the court when the opportunity presents itself.
"He's not going to fill up your fantasy sheet and all that kind of stuff. But he's who every coach and every player wants on their team."Celtics president Danny Ainge, on Al Horford's impact for Boston
To hammer home just how much of a quarterback Horford has become in Boston, consider this: According to Second Spectrum data, Horford is setting up 14.6 shots per 100 possessions this season. That's up from 9.6 shots per 100 possessions in his final two seasons in Atlanta. Horford has had 19 games with six assists or more this season, the highest number among all NBA centers.
"It's a big credit to [Horford]. He's changed and I think Brad's open enough to give him even more responsibility," said Nets coach Kenny Atkinson, who was an assistant in Atlanta during Horford's time with the Hawks.
"Sometimes as coaches we hold back guys. I can even see with Brad he's doing even more things than he did in Atlanta. I see him handle the ball a lot more at the top of the key and bringing the ball up sometimes. It's impressive.
"I know Al was thirsty and hungry to kind of embrace that new big-man role. And he didn't shy from it. That was the thing that impressed me in Atlanta. When we asked him to do more, get out of his comfort zone, he embraced it."
Horford's base stat line doesn't exactly scream "All-Star" but he's averaging 13.3 points, 7.8 rebounds and a career-best 5.3 assists this season. His evolution is further emphasized by the fact that he's shooting 43.5 percent beyond the 3-point arc, which ranks him tied for eighth overall in the NBA, a few spots ahead of former Atlanta teammate Kyle Korver.
Horford has nearly as many 3-point makes this season (64) as he had attempts (65) through his first eight NBA seasons.
"As good as Kyrie [Irving] is offensively, it's almost like Horford is the sort of the hub of everything they do," Sixers guard JJ Redick said. "And because [Horford is] so versatile, it creates all sorts of issues."
The Celtics entered the week with the NBA's best defensive efficiency (99.8), and much of that success can be traced to Horford, who was allowing a mere 0.77 points per play, according to Synergy Sports data. Of the 45 highest-volume players with at least 500 plays defended, Horford ranks No. 1.
NBA defensive tracking data suggests that Horford is limiting opponents to 41 percent shooting overall, or 5.8 percent lower than those players' season average, and NBA hustle data ranks Horford tied for fourth in the league while contesting 13.1 shots per game.
Horford's ability to impact both ends of the floor is part of the reason why Vogel gushed about him in November: "He doesn't have that superstar persona but, in my mind, he is [a superstar]."
None of this comes as a surprise to Sweet, who still watches Celtics games from afar. Sweet remembers Horford knocking on his door on Sunday mornings and asking him to open the weight room when the team was otherwise not scheduled to practice.
"His overall knowledge, his basketball IQ, it's just out of this world," Sweet said. "He's just like a sponge, he just wants to learn more and more."
The first time Horford tried to alert the Celtics of his decision to sign with the team during the summer of 2016, he landed in Danny Ainge's voicemail.
Boston's brain trust was on a private plane in the Hamptons, taxiing out to the runway after their meeting with Kevin Durant when Stevens' phone buzzed with Horford's second attempt.
Celtics owner Wyc Grousbeck implored the pilot to pull off the runway while the team fielded the call.
"I've given it some thought and," Horford said while letting the anticipation build. "I want to be a Boston Celtic."
Horford could hear Boston's celebration on the other end of the phone. While the rest of the NBA was caught up in the Durant sweepstakes, the Celtics had quietly buried the notion that Boston couldn't land a big-name free agent.
"Don't look at his stat line. Look at how many games he's won in his life."Celtics assistant coach Jay Larranaga
Horford, who had a dozen suitors at the start of free agency, had initially whittled his list to eight teams, one of which was the Thunder, but uncertainty over the future of the Durant-Russell Westbrook relationship might have caused trepidation despite the presence of his former college coach in Billy Donovan.
Horford ultimately took four meetings on July 1, spending time with representatives from the Celtics, Rockets, Wizards and Pistons -- all while remaining in communication with the Hawks about a possible return. All four visitors brought their A-games, including the Rockets, whose contingent featured James Harden.
A Boston team -- losers to the Hawks in the opening round of the 2016 playoffs two months earlier -- came with Isaiah Thomas, Jae Crowder and Kelly Olynyk with a goal of emphasizing Boston's young nucleus. Grousbeck wore his 2008 championship ring.
Horford, who has recently professed a love of coaches, might have ultimately been most moved by Stevens, who led a presentation on how exactly Horford would be utilized in Boston. It was the straight X's and O's that Horford craved.
It was so very Horford-like that his quiet free-agency decision essentially got overshadowed by Durant's dog-and-pony show in the Hamptons (one that the Celtics contributed to by bringing Patriots legend Tom Brady for their pitch).
Still, getting that call from Horford was reason for celebration.
"It was a big moment," Danny Ainge said. "We needed a guy like Al. We needed a veteran for our young guys. We needed a guy who only cared about winning. That was a huge moment for our franchise."
During his introductory news conference, Horford said that he hoped his arrival would "open the door" for other big free agents. The next summer, Gordon Hayward had enough faith in Boston to do what Horford did -- leave the familiarity of the only NBA team he knew to join Boston's title quest.
The trade that added Irving in late August forced Boston to sacrifice some of its depth and left the Celtics thin on experience at the end of their roster. They could do that with confidence that Horford would provide veteran leadership.
"They say like the moment you stop wanting to get better is the moment you stop being good," Celtics assistant coach Jay Larranaga said. "[Horford] never stops wanting to get better, so his standard for what is acceptable and what his goals are is very very high."
To be sure, Horford isn't wrong when he says that he is not without his detractors. There are many Celtics fans who see his $27.7 million salary and yearn for more tangible production.
Horford's All-Star nod might help identify some additional haters. During TNT's broadcast announcing All-Star reserves, Shaquille O'Neal opined: "Al Horford got a lot of credit because Boston is 34-13. As a big guy, 13 [points] and [seven rebounds] aren't All-Star numbers to me."
Former Boston Red Sox infielder Lou Merloni, who hosts a midday show on Boston sports radio WEEI, has nicknamed Horford "Average Al" and often laments whether he's worth the price tag. That has drawn the ire of more outspoken Horford family members, like Horford's father, Tito, and his sister, Anna.
For those who get hung up on basic stats, Larranaga has simple advice.
"Don't look at his stat line," Larranaga said. "Look at how many games he's won in his life."
Horford is humbled when it's noted that the search for an NBA detractor has turned up empty. When it's suggested that that's the ultimate sign of respect from his brethren, Horford downplays the suggestion.
"That's a nice compliment. But not everybody is going to love you," Horford said. "You're always going to have people like that. I've been lucky enough to always recognize to leave stuff on the court, on the court. And I think a lot of pros these days do the same. I don't have a problem with anybody.
"Until I get on the court."