At the time, some wondered if the Knicks had made a mistake in trading for Grant on the night of the NBA draft.
But if games like Tuesday's are any indication, the rookie will be just fine. Maybe more than fine.
"When he comes in, putting pressure on the defense, it changes the dynamic of the game," Carmelo Anthony said.
Grant changed everything for the Knicks in the final minutes against the Celtics. He had 10 points and six assists in the fourth quarter to help the Knicks (20-20) walk off the floor with the win.
Not bad for someone who played a total of 17 minutes over a four-game stretch in mid-December.
"He was waiting for that moment," Porzingis said. "He was ready for it. He was fearless out there."
Grant's success on Tuesday was a product of his extensive work on the practice court. When he was out of the rotation, Fisher would see Grant on the court several hours before practice, working on his craft.
"Taking a lot of jump shots and really working on the triangle and things like that," Grant said. "I've been in the gym and it showed a little bit tonight."
It certainly did, though Grant wasn't the sole reason New York beat its division rival on Tuesday. The Knicks had to rely on several reserves in the closing moments of the game because Anthony (17 points) was sidelined with a sprained ankle and Kristaps Porzingis (26 points, six rebounds) was out due to foul trouble.
So it was a good night for Phil Jackson's offseason acquisitions.
But the biggest plus for the Knicks was the play of Grant, who didn't turn the ball over in 23 minutes. The former Notre Dame star also assisted on 47 percent of New York's field goals while he was on the floor.
"He stepped up big-time," Anthony said. "He controlled our team, controlled our offense, attacked their defense. He made big plays."
Some may see this as evidence that Grant deserves minutes over starter Jose Calderon. But Calderon has played a significant role in the Knicks' recent success. And the idea that Grant drastically changes the pace for New York may be a fallacy. On Tuesday, the Knicks ran 102 possessions per 48 minutes with Calderon on the floor and 94 possessions per 48 with Grant out there.
Still, New York can certainly use more nights like this from Grant going forward. The point guard position has been an inconsistent spot for the Knicks thus far.
The club had been looking for backcourt help via free agency or the trade market in recent weeks, according to sources. Players like Jimmer Fredette, Tony Wroten and Brandon Jennings are on the team's radar, sources familiar with the team's thinking say.
But if Grant continues to play as well as he did Tuesday, there may be no need to make a move. Maybe all the Knicks need is a little more Jerian Grant.