When the Celtics traded Rajon Rondo to the Dallas Mavericks last season, they did so mainly because they got a protected first-round pick in return.

The fact that Jae Crowder was also in the deal didn’t mean much. He was a role player at best on the Mavericks. The Celtics, at the time, had a team of role players. The Celtics didn’t really know for sure what they were getting in Crowder. And the feeling was mutual on Crowder’s end — at a time where he was due to hit free agency at the end of the season.

But it didn’t take long to see that Crowder had more to his game — and his personality — than most expected.

Not soon after, Jeff Green was shipped to Memphis, which opened up even more playing time for Crowder.

The C’s then traded for Isaiah Thomas, and along with Crowder the two helped lead the team to the playoffs. It was apparent by then that Crowder and Boston were a match. He was tough, he was energetic and he provided a huge spark to a young team coming together down the stretch.

And this season, after re-signing for five years and $35 million (which feels like a steal), Crowder has been even better, adding leadership to his growing arsenal of attributes.

Crowder is averaging 13.9 points and 5.3 rebounds per game in his first full season with Boston. His points are up from 9.5 per game last season with Boston, and just 3.6 per game in Dallas before the trade. But his 1.20 steals per turnover this season ranks him 9th in the NBA, and describes the kind of player he is out there.

Though just 25 years old and in his fourth NBA season, Crowder feels like he’s been in the league much longer. And after what he knew was a disappointing showing against the Nets in front of the home crowd over the weekend, Crowder made sure he and his team brought it in the rematch two days later.

He finished with a career-high 25 points to go along with six rebounds and three steals. The performance had Brad Stevens telling reporters after the game how he’s “not afraid of the big moment.”

But Celtics fans who have watched him play over the last year already know that.

“We tried to learn from our mistakes and come out here and play the way we wanted to,” Crowder told CSNNE after Monday’s win over Brooklyn. “We didn’t play the way we wanted to back at home so we knew we needed this win. We came out and played.”

The Celtics have struggled with inconsistency this season, and Crowder will be the first one to tell you that. But watching him evolve with the team, it’s no wonder why he’s quickly become a fan favorite here in Boston.