"I think this year will tell us a lot more," Ainge said Tuesday morning of Walker, who the team announced will be out until at least January after he was given a stem cell injection and put on a 12-week strengthening program after last season ended.
"He saw some specialists over the last six or eight weeks, and they all came to the same conclusion, and I think that gave Kemba a great peace of mind as he went to different, really good doctors in our country and got the same opinions. He's on a program, and he seems to be in a very good, happy spot."
Ainge said the expectation from those meetings was that surgery would not be necessary.
After the Celtics signed Walker as a free agent to a four-year max contract in the summer of 2019 to replace Kyrie Irving, he spent the latter portions of the regular season dealing with ongoing soreness in his left knee -- particularly after the All-Star break -- before the season was suspended March 11.
Then, once teams resumed on-court work in late June ahead of the NBA restarting its season in late July, Walker had another setback with his knee, and was put on a minutes restriction both during the weeks leading up to the restart and throughout the seeding games inside the league's bubble at the Walt Disney World Resort in Orlando, Florida.
Walker looked very good against the Philadelphia 76ers in the first round of the playoffs, but he struggled as the Celtics progressed throughout the postseason -- particularly after taking a hard fall during the second round against the Toronto Raptors when he appeared to tweak the knee.
Ainge said it was possible Boston rushed Walker back too quickly for the bubble -- a touchy subject in Boston, given the history surrounding Isaiah Thomas after his hip issues following Boston's run to the Eastern Conference finals in 2017 -- before almost immediately walking back his own statement.
"Maybe we didn't do him justice by bringing him back too fast into the bubble, being hurt and finding some urgency to get him ready during the regular season," Ainge said. "We don't want to make that mistake, if it even was a mistake, this time. I'm not blaming anybody. It's not a perfect science. It's guesswork, and we're trying to do the best with the information that we have and get him as strong and healthy as he can be, so he's ready to make it through the year."
But just when Walker's season will start -- and when he will be a full participant for the Celtics -- remains very much up in the air. The Celtics said in their statement that Walker's game-availability status will be updated in the first week of January, which is roughly when his 12-week strengthening program should end.
That doesn't mean, however, that Walker is going to begin playing 30-plus minutes a game. Instead, the expectation is that Walker will slowly be ramped up over time, in a similar fashion to the restart in Orlando.
Celtics coach Brad Stevens said Walker's return was affected in part by the fact that the NBA season is getting started sooner than everyone had anticipated.
"Well, I think this has as much to do with the turnaround as anything else," Stevens said. "I think if we were starting games in the middle of January, he'd probably be starting right along with us and I don't even know if we'd be talking about it. So I do think that it's very similar to what I said when we got to the bubble: This is about making sure that he feels great, strengthening appropriately, moving at the right pace, and hopefully playing his best basketball.
"I know he's very committed to that. He's had great work over the last few weeks with regard to strength, but we are going to proceed slow, and I do think the expedited timeline on Dec. 1 impacted him quite a bit in regard to his own timeline of starting the season on time."
Further complicating Boston's situation with Walker is having to deal with the loss of Gordon Hayward, who officially signed as a free agent with the Charlotte Hornets on Sunday after the two teams eventually agreed to a sign-and-trade deal. Ainge wouldn't go into specifics about negotiations on potential sign-and-trade deals with other teams, but he did confirm that the Indiana Pacers were one of them. And, when asked about Hayward's departure, he praised him for choosing to come to Boston as a free agent three years ago, and for coming back in the bubble just four weeks after suffering a Grade 3 ankle sprain to play the final three games of the Eastern Conference finals against the Miami Heat.
"Let me just start off by saying I'm grateful Gordon chose Boston," Ainge said. "I wish him nothing but the best. He's a good teammate, a good guy, a terrific player, and I'm grateful that Gordon missed the birth of his son and came to play and try to help us even though he was far less than 100 percent this year in the playoffs.
"He made sacrifices to try to give us a better chance of winning. It didn't work out for our team, but I'm grateful that he gave that kind of effort and his family gave that kind of sacrifice. I wish Gordon nothing but the best and congratulate him on his new deal in Charlotte."
The Celtics will also be without second-year forward Romeo Langford until at least late January, and likely longer, as part of a four-to-five-month recovery timeline from surgery to repair a torn ligament in his right wrist on Sept. 22.
"We'll see once we go through practice, get into the games, where we're strong, where we need a little bit of help," Stevens said. "We'll have some help coming at some point because we've got a few guys that are out.
"But early on in the year, we're going to find out a lot and guys are going to get opportunities that they'll have worked hard for, that they'll have earned through the first few weeks of the season, and that are going to be more available because we've got a few guys missing."