“This year, everything is coming together for our group,” Celtics center Al Horford said in an exclusive interview with Stadium. “I feel like this is the best group we’ve had since I’ve been here.”

Horford signed a four-year, $113 million deal to become Boston’s first major splash in free agency back in 2016. He wasn’t a star, but Horford provided an all-around player for the Celtics to construct a contender around. Horford ultimately committed to a team with no established stars, but was sold on Brad Stevens, who had proven himself to be a strong coach.

“I think it all starts with Coach Stevens,” Horford observed. “We are all buying into his system and how he wants us to play on defense.”

With Horford providing mobility at the center position, Stevens is able to have his team switch 1 through 5 defensively and prevent the 3-point shot from hurting Boston.

Although Boston is better on the court defensively this year when Horford sits, this metric is likely due to his heavy minutes against opposing starting lineups. Horford’s individual defensive rating is 104 this season as opposed to 103 from a year ago, so he’s maintained a strong level of play on that end, and his 4.7 block percentage this season would be a career high.

But it’s Horford’s impact on the offensive end that has given Boston a much-needed boost this year.

The Celtics have been 16.4 points better per 100 possessions with their starting lineup this season, due in large part to Horford’s efficiency. The big man has maintained his production, with his points per game and rebound percentage matching last season’s marks despite seeing fewer minutes per game. His assist rate is down, but so is his turnover rate.

Horford sat out during a seven-game stretch earlier in the year. During that time, the Celtics went 4-3 and struggled to score. But Boston has rebounded with Horford back in the lineup, going 17-6 in their last 23 and establishing themselves as a legitimate threat in the Eastern Conference.

Horford can opt out of his $30.1 million player option for next season, which seems highly unlikely. Boston will be content keeping him due to his two-way abilities, but a lot depends on Kyrie Irving’s fateful decision. If the guard leaves in free agency, the Celtics could dangle Horford as an expiring contract at the trade deadline.

When asked about Irving’s recent antics, Horford said that the team tries to look past these distractions, but recognizes the chatter.

“You really try not to talk about it too much, but it’s there,” Horford revealed.

As for another team in the news, the 76ers just acquired forward Tobias Harris to bolster their playoff chances. Harris is having a career season offensively and provides Philadelphia, who the Celtics beat last postseason, with one more weapon.

“Tobias is a great player and it just makes them that much better,” Horford said. “That starting five is ridiculous.”

There’s one clear reason the Sixers made the deadline move to add Harris: to keep up with the Celtics. After an early-season rut, the Celtics are behind only the Bucks and Raptors in the East and are starting to look more like the team projected to run away with the Eastern Conference.

If this truly is the best Celtics team that Horford’s played for, Boston could be preparing for the NBA Finals come June.