Boston Celtics at Orlando Magic game preview

The Boston Celtics have built an identity the last few years under Brad Stevens as a tough-minded defensive team.

His offensive brilliance with a mismatched roster without a star has always had the stout defense as a backdrop.

To take that next step, Boston added Al Horford to Isaiah Thomas, hoping they would propel the club to the top of the Eastern Conference. They believed Horford would only bolster their defense.

Horford has indeed helped, notwithstanding the failed tip-in at the buzzer against the Houston Rockets on Monday. Boston is sitting at 12-9 and in third in the packed Eastern Conference.

Orlando Magic on FOX Sports Florida

The defense, though, has been slow to develop.

In 2015, the Celtics finished 12th in defensive rating on their way to a surprise playoff berth. Last year, Boston finished fourth in that metric.

This year, however, Boston is 17th in defensive rating, giving up 105.1 points per 100 possessions. Boston is still winning, but the team has struggled to bring its defense to the elite level that it one of the rising teams last year.

The defense has improved recently. In the last 10 games, the Celtics are 11th in defensive rating, giving up 104.8 points per 100 possessions. Boston is still carving out an identity with the new players on the roster.

The Celtics’ opponent Wednesday, as they wrap up a three-game trip, has found that identity in the last month.

While the Celtics have been trying to elevate their defense, the Orlando Magic have become one of the top defenses in the league.

Orlando had given up just 94.3 points per 100 possessions in 10 games before a 124-116 win over the Washington Wizards on Tuesday. The Magic have risen to third in the league as defense has become a key part of their identity.

No player has embodied that improvement more than Nikola Vucevic, who had a reputation as a poor defender but has quickly become one of the biggest defensive stalwarts for the Magic this season.

"Everybody has been really so hard on my defense," Vucevic told the Orlando Sentinel. "I think there is no player in this league that does everything. So there are areas that I do really well defensively (and) some areas that I need to improve, and I think I did improve on those this year. I never felt like my defense was that big of an issue. It was just all the media making a big deal out of it."

The Celtics will hope to get their defense back on track against the Magic. They may have to do it without Thomas. The All-Star point guard missed Tuesday’s practice with a pulled groin, but he told The Boston Globe he still hopes to play Wednesday.