Maddie Meyer/Getty Images

An 18th NBA championship banner might be hanging in TD Garden if the Boston Celtics hadn't traded Isaiah Thomas—at least in the eyes of Thomas.

"Yeah, we would have probably won a championship already," the Denver Nuggets point guard said Monday after his team's 114-105 win over the Celtics, per ESPN.com's Chris Forsberg.

The two-time All-Star wore a customized green-and-gold pair of Kobe Bryant's signature Nike shoe.

He also revealed those shoes were made with an eye toward suiting up in the Finals for Boston, per NBC Sports Boston.

Thomas was obviously feeling nostalgic upon his return to Boston. The team played a video tribute to him celebrating his two-and-a-half years in Celtics green.

The Celtics lost in the opening round of the 2016 playoffs but advanced to the 2017 Eastern Conference Finals, losing to the Cleveland Cavaliers in five games.

The 2017 postseason proved to be significant for Thomas personally as he continued to play through a hip injury until bowing out after Game 2 of the conference finals.

The 30-year-old hasn't been himself since the injury. Prior to Monday night, he was averaging 13.7 points on 37.3 percent shooting from the field across 41 games with the Cavs, Lakers and Nuggets. He was also a 29.0 percent shooter from beyond the arc. The explosion he showed off the dribble simply hasn't been there.

The Nuggets waited nine games before dropping him out of the rotation, though he played seven minutes against Boston.

Because of his rapid decline, it's hard to see how the Celtics would've had a better shot at winning a title with Thomas in place of Kyrie Irving, the star whom Boston acquired to be the new starting point guard.

One could also debate whether the Celtics' young duo of Jaylen Brown and Jayson Tatum make the jump they did in 2017-18 with Thomas on the floor.

According to Basketball Reference, Thomas had a 34.0 percent usage rate in 2016-17 compared to 31.0 percent for Irving a season ago. Losing Irving for 22 regular-season games and the entire postseason forced Tatum and Brown to step up as well, indirectly furthering their development.

And that's to say nothing of how the Golden State Warriors would've tried to expose Thomas' defensive flaws on every possession were Boston to get to the NBA Finals.

Thomas enjoyed the best basketball of his NBA career with the Celtics, but he might be reaching a bit to say his departure damaged the franchise's championship hopes.