How the Isaiah Thomas trade altered Celtics history 10 years ago

How the Isaiah Thomas trade altered Celtics history 10 years ago originally appeared on NBC Sports Boston

One day after his Boston Celtics secured their NBA-record 18th championship last June, head coach Joe Mazzulla made a point to credit the former C’s players who played a role in the team’s long journey to Banner 18.

“You can’t lose sight of the people that came before us,” Mazzulla said.

That brings us to Isaiah Thomas, the 5-foot-9 guard who came to Boston exactly 10 years ago this Wednesday via trade from the Phoenix Suns and helped turbo-charge the Celtics’ return to prominence.

Here’s a refresher on that Feb. 19, 2015 deal, which at the time didn’t generate much buzz amid a flurry of NBA trade deadline moves around the league:

• Celtics receive: Isaiah Thomas

• Suns receive: Marcus Thornton, 2016 first-round pick (Skal Labissiere)

Thomas had been a solid role player for the Suns during the 2014-15 season, averaging 15.1 points per game off the bench prior to the deadline. But in a sign of things to come, Thomas elevated his game down the stretch, averaging 19.0 points to help the rebuilding Celtics go 20-11 down the stretch and make the playoffs as a No. 7 seed. (For context, the 2013-14 Celtics won 25 games all season.)

The rest is history: Thomas thrived as Boston’s starting point guard in 2015-16, averaging 22.2 points per game to make his first All-Star team as the C’s went 48-34 to earn the Eastern Conference’s No. 4 seed before falling in the first round to the Atlanta Hawks.

A year later, Thomas had one of the best seasons in franchise history, pouring in 28.9 points per game — at the time the second-highest single-season scoring average by a Celtics player behind only Larry Bird — to carry Boston to its first 50-plus-win season since the Big Three era.

Thomas’ heroics during the 2017 playoffs are the stuff of legends; he exploded for 53 points in Game 2 of the East semifinals against the Washington Wizards, then dropped 29 in Game 7 to help lift the C’s to the East Finals.

Thomas’ Celtics career ended after that postseason, as Danny Ainge dealt him to the Cleveland Cavaliers in a stunning trade that brought Kyrie Irving to Boston. But despite playing just two-and-a-half seasons in green, his impact is undeniable.

Entering the 2015 trade deadline, the Celtics were a lottery team searching for an identity under new head coach Brad Stevens following the breakup of the Big Three. Enter Thomas, and undersized guard with outsized passion who wore his heart on his sleeve and was immediately embraced in Boston.

Thomas, along with the likes of Marcus Smart, Avery Bradley and Jae Crowder, helped establish the Celtics as a gritty team that could outwork opponents despite a relative lack of talent. By the time he left, the C’s were viewed as serious contenders that could attract big-name free agents like Al Horford, who signed a four-year, $113 million contract with Boston in the summer of 2016 and paved the way for Gordon Hayward to sign a max contract with the Celtics the following offseason.

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The C’s obviously went through several roster iterations before raising Banner 18 in 2024, and the development of homegrown talents Jayson Tatum and Jaylen Brown played a key role in getting them over the hump.

But you could argue their recent success doesn’t happen without Thomas, who helped put the Celtics back on the map by turning a lottery team into a playoff contender, in turn attracting real talent to Boston for the first time since Paul Pierce, Kevin Garnett and Ray Allen left town.