Perhaps the most encouraging thing for Kelly Olynyk last night was that in only his second game this season, and his first start, the fluidity returned to his offense.

From shooting 3-for-5 from 3-point range to finishing with 17 points and three assists during the Celtics’ 115-87 win against the New York Knicks at the Garden, the forward didn’t look like a player returning from shoulder surgery.

Or maybe his lengthy rehabilitation was well worth the time.

“I felt a little more comfortable getting back on the floor,” Olynyk said. “It’s tough. I haven’t played a game in five-and-a-half months, so to be able to get back Wednesday night and follow it up with tonight just feels better.”

Before the game, Stevens had no hesitation moving Olynyk into the starting lineup.

“I’m not worried as much about how to use somebody or not,” Stevens said. “I think I probably have a better understanding of Kelly than anyone else on our team because he’s been here the whole time (since the coach was hired in 2013), other than Avery (Bradley). So you know there’s always going to be some transitioning back, but let’s get that part of the process moving. Like, let’s transition him back and then we’ll have to do the same thing with Al when he comes back.

“We’ll have to do the same thing with Jae (Crowder, out with an ankle injury) when he comes back. And that’s why, like I mentioned earlier, we have to take a step back and say, OK, the bottom line is we need to play better. But we’re far from a finished product. And we’ll get better.”

Horford on hold

Al Horford is attempting to come back from one of the most difficult injuries to measure, a concussion, and as evidenced by his fourth straight scratch, the Celtics big man’s status is as imprecise as ever.

Horford was encouraged by the news he will join the team for a two-city road trip that begins tonight in Indianapolis and concludes Monday in New Orleans. He allowed that he could play in either or both games, or miss both.

That’s the nature of the injury.

“I’ve been banged in the head before, but nothing like this,” Horford said.

Asked about his symptoms, Horford declined to get specific.

“I don’t think I can talk much about that right now,” he said. “If I’m good to go, I’ll be more than happy to talk to you about that.”

NBA concussion protocol stipulates that a player be symptom-free for 24 hours, and Horford couldn’t say for sure that he had reached that point. The encouraging part: He was able to run.

“I’m getting better each day, and the past two days have been really good for me,” he said. “I was able to get on the court a lot more and run up and down. Do a lot of movement, a lot of stuff I wasn’t able to do a couple of days ago. . . . I’m just looking forward to getting back. It’s been hard for me to sit on the side. I’m looking forward to getting it rolling again with the guys.”

The process has been just as imprecise for those monitoring Horford.

“I don’t want to even act like I’m a doctor, but from what I understand each concussion is unique,” Stevens said. “It was diagnosed as a mild concussion, but as long as there are symptoms that reoccur then that continues the protocol. And that’s good. I’m thankful I’m coaching in an era where that’s the case. The most important thing is that his health is prioritized. And mild or not, a concussion’s a concussion.”

That hasn’t made Horford’s status as a spectator any easier to accept.

“It’s been difficult just because you want to be out there helping your teammates, fighting every night,” he said. “It’s tested my patience this time.”

Altered lineup

In an attempt to make up for the team’s defensive and rebounding ills in the absence of Horford and Crowder, who is still approximately a week removed from returning, Stevens sent out a starting lineup of Isaiah Thomas, Bradley, Marcus Smart, Amir Johnson and Olynyk.