Brad Stevens continues to add pieces to the Celtics roster, and will likely make a few more moves this offseason. Corey Sipkin/Associated Press

The target date of July 18 came and went for the Boston Celtics, meaning a $17.1 million trade exception officially expired. Boston gave up draft assets to create the Evan Fournier exception last offseason, but even without taking advantage of it, the front office already made huge moves to upgrade the roster.

The Celtics are contenders going into next season. President of Basketball Operations Brad Stevens didn’t touch the roster’s core, instead putting together the Malcolm Brogdon trade by sending away a first-round pick and multiple bench pieces. The Celtics also signed Danilo Gallinari, who they wanted as a consistent bench scorer.

So how else can the Celtics upgrade their roster? The league slows down after the NBA Summer League, but the Celtics should still sign a few more players to their roster ahead of training camp. Then the Celtics will look to protect their Eastern Conference crown and earn another trip to the NBA Finals.

“I really value how a team fits together, and how everybody brings their strengths to the table and accentuates each other,” Stevens said. “We’re deep, but we have a lot of options. … We talked about how it’s great to have the green light to continue to add whatever we need. But one of the things I’ll continue to focus on is adding without taking away.”

The Celtics have 12 players under contract, along with filling up both their two-way slots. That means the final few roster spots will likely be a competition at training camp. The Celtics have the luxury to sink their teeth into whatever available options are still left on the free agent market or elsewhere.

Immediately, the Celtics will likely look for another big man behind Robert Williams III and Al Horford. Boston already has Luke Kornet inked to a deal, along with recent two-way signee Mfiondu Kabengele, who impressed in five games in Las Vegas.

But another capable big man could be crucial for the Celtics. Williams has been injury prone throughout his career, and the team will be conservative with the minutes of the 36-year-old Horford. Another big man who can provide spot minutes is crucial.

Celtics Coach Ime Udoka also mentioned the team is going to look for another wing option. Boston is clearly high on Sam Hauser, who signed a guaranteed deal earlier this offseason. Beyond that, the Celtics could look at guys like Matt Ryan, Justin Jackson, Brodric Thomas in training camp, all of whom played in the NBA Summer League and showed some good things.

Realistically, adding another rotation piece through the trade exception was going to be difficult not just from a cost standpoint but also practically speaking. The Celtics have one of the deepest benches in the league, and there are only so many minutes to go around. While Boston ran out of gas in the Finals, that shouldn’t be a problem as long as everyone stays healthy next season. Udoka also has plenty more options to play on a nightly basis.

“We’re just monitoring everything we’re doing here, taking a good look at our guys,” Udoka said.

The Celtics will be billed as one of the best teams in the league next season – and rightfully so. That’s not accounting for any natural improvement from Jaylen Brown and Jayson Tatum. There were growing pains ahead of their Finals run, but continuity doesn’t hurt as Udoka enters his second year as head coach.

Stevens hit mostly singles last year, dabbling with the edges of the roster. He brought in Horford and Derrick White, both of whom were important players in the playoffs. While Stevens hit an extra-base hit on the Brogdon trade, he should be back to hitting singles when it comes to the final spots on the roster.

“It has been whatever we need to do to try to maximize our opportunities, and we obviously have a really good core, a really good team, and fortunate to make these two really good additions,” Stevens said. “We wouldn’t be able to do that without that commitment from (ownership). We’re obviously thankful. We’ve had the green light the whole time to make those calls.”