Stephen Curry appeared at a recent practice for the Golden State Warriors without a walking boot on his sprained left foot. In Los Angeles, the Clippers’ Kawhi Leonard, who has not played all season, was spotted by local reporters participating in shooting drills. And the Denver Nuggets’ Jamal Murray, also sidelined since last season, is again soaring for dunks, according to some impeccable sources: his own teammates.

“Just a matter of time, I guess,” Nuggets guard Monte Morris told reporters recently, “so hopefully we can get him back and make that push.”

Ahead of the start of the N.B.A. playoffs on Saturday, a slew of teams, many of them contenders, could be primed for makeovers. Golden State could stage an on-court reunion of its Big Three — Curry, Klay Thompson and Draymond Green — for the first time in the playoffs since 2019. The Nuggets have left the door ajar for Murray’s long-awaited return from knee surgery. The Clippers only recently reintroduced Paul George to their starting lineup after he had been absent since December with a torn ligament in his elbow, and is it possible that Leonard, who injured his right knee last June, could make a surprise appearance in the coming weeks?

The list goes on. Ja Morant, the All-Star point guard of the Memphis Grizzlies, just returned from injury over the weekend. And there are teams like the Nets, who now have the luxury of playing Kyrie Irving in home games, and the Milwaukee Bucks, the defending champions, who have been building Brook Lopez’s minutes after he missed 67 games with a bad back. Chris Paul of the Phoenix Suns is getting back into rhythm after missing a month with a thumb injury.

What does it all mean? Potential headaches for opponents, and an undercurrent of unpredictability that will run through the early rounds of the postseason.

“I think it’s unusual that we’re waiting to hear about that from so many teams,” Stan Van Gundy, the former N.B.A. coach, said in a telephone interview, “and that guys could come back in the playoffs who either haven’t played all year or for a good part of the year.”

Facing teams with stars who may or may not play creates a unique set of challenges for opposing coaches, said Eric Musselman, a former coach of the Warriors and the Sacramento Kings who now coaches the men’s basketball team at Arkansas. On the one hand, he said, you want to relay to your team that the injured player will be a threat if he actually appears in uniform.

“I’ll never say, ‘This guy might be out of sync,’ or, ‘He’s going to be rusty,’” Musselman said. “It’s always: ‘This guy is an All-Star, he’s been working out, and he’s in playoff shape.’ You need to be ready for anything.”

On the other hand, Musselman said, you need to guard against a letdown in focus and intensity if that player winds up sitting out. Uncertainty, in its own way, can create a competitive advantage.

So even if the Nuggets decide not to play Murray in the playoffs, or the Nets officially pull the plug on Ben Simmons and his balky back, it might behoove those teams to keep that information to themselves, Van Gundy said. There is no harm, he said, in leaving opponents guessing. Force them to concoct multiple game plans. Make them plan for something that will never happen.

“I’m going to want to add to your preparation time,” said Van Gundy, now an analyst for TNT and Turner Sports.

Van Gundy cited the Orlando Magic’s 2009 playoff run when they faced the Boston Celtics in the Eastern Conference semifinals. Kevin Garnett, the Celtics’ star center, had been sidelined for several weeks with an injured knee, and Van Gundy, who was the Magic’s coach at the time, said he knew there was “virtually no chance” that Garnett would make an appearance in the series. But Garnett was still a presence on Orlando’s scouting report, and the team still studied film of him.

“If he came back, we didn’t want to lose a game in a seven-game series because we got caught by surprise,” Van Gundy said.

Over the coming days and weeks, opposing coaches will overprepare for the possibility that long-injured stars could return, said Brendan Suhr, a former longtime N.B.A. assistant. And if one does?

“I’m immediately going to trap him,” Suhr said. “I’m going to try to do stuff he’s not used to seeing. I would make it very difficult for him. Because his workouts, especially his noncontact workouts, were very soft — coming off pick-and-rolls, getting into rhythm, making shots. And now I’m going to force him to make very tough, under-pressure decisions.”

At the other end of the court, make that player defend. “Especially if he’s coming back from a leg injury,” Suhr said.

With all that in mind, teams with stars on the mend must weigh the delicate calculus about whether to bring them back at all — and if so, when. Will they be ineffective? Susceptible to further harm? Van Gundy recalled a conversation he had with Tyronn Lue, the coach of the Clippers, last month, before George returned to the team’s lineup on March 29.

“He was talking about how there would be a cutoff point in terms of bringing Paul George back,” Van Gundy said. “If he couldn’t get in X amount of regular-season games, he wouldn’t want to play him in the playoffs.”

There are, of course, cautionary tales from playoffs past. Consider Golden State’s tortured postseason experience in 2019, when Kevin Durant, who was then one of the team’s stars, strained his right calf in the Western Conference semifinals. After missing nine straight games, he returned for Game 5 of the N.B.A. finals against the Toronto Raptors and ruptured his right Achilles’ tendon. The Warriors lost the series, and Durant missed the entire 2019-20 season after signing with the Nets.

Michael Malone, the coach of the Nuggets, told reporters this month that Murray “wants to be back” and that the team was “keeping hope alive.” Nikola Jokic, the Nuggets’ do-everything center and a favorite to repeat as the league’s most valuable player, sounded more cautious about the situation.

“I told him, ‘If you’re not 100 percent ready to go, don’t come back,’” Jokic said. “It’s stupid. You’re going to get injured. I mean, if you’re not 100 percent ready to go, especially for the playoffs. …”

His voice trailed off.

After getting past the Garnett-less Celtics in 2009, the Magic advanced to the N.B.A. finals that year against the Los Angeles Lakers. Ahead of Game 1, Van Gundy decided to activate Jameer Nelson, his starting point guard. Nelson had missed the previous four months with a torn labrum in his right shoulder. Van Gundy opted to bring him off the bench against the Lakers.

“He was our leader, and he was having an All-Star year until he got hurt,” Van Gundy recalled.

And because Nelson was returning from a shoulder injury, that meant that he had been able to run and stay in relatively decent shape during his long layoff.

“That’s a little different than if you’ve got a knee injury and you’re limited in what you can do,” Van Gundy said.

Still, even with Nelson back in the rotation, the Magic lost the series in five games. Van Gundy has never regretted the move.

“You want to go into the biggest games with your best people,” he said.