Marcus Smart’s season hung in the balance of a New York hand specialist. “I think there’s a chance he plays and a chance he’s done,” Boston Celtics president of basketball operations Danny Ainge told 98.5 The Sports Hub on Thursday. “We’re all waiting to figure out what that’s gonna be.”

The diagnosis dropped Friday on Smart’s injured right thumb — suffered diving for a loose ball late in the third quarter of Sunday’s loss to the Indiana Pacers — and it landed somewhere in the middle:

The surgery to repair a torn tendon in Smart’s right thumb, which will reportedly cost him at least the final 15 games of Boston’s regular season, comes on the heels of season-ending torn left meniscus surgery for reserve center Daniel Theis. Coupled with Kyrie Irving’s chronic left knee soreness, Jaylen Brown’s concussion and Al Horford’s illness, the second-place Celtics are limping into the playoffs.

This, of course, after losing All-Star forward Gordon Hayward to a horrific leg injury five minutes into the season. Where once there was hope Hayward could return in the playoffs — a long-shot that got longer with Ainge’s announcement that he had suffered a slight setback in his rehab — the Celtics are now just hoping they can patch together a rotation to save another surprising 50-win campaign.

Smart’s absence is a devastating blow to their chances of making the Eastern Conference finals, much less the NBA Finals. While his traditional statistics — 10.2 points (on abysmal 36.7 percent shooting), 4.7 assists and 3.5 rebounds in 29.9 minutes per game off the bench — aren’t overwhelming, his manic play, especially on defense, breathed life into a briefly thriving second unit that is now in shambles.

With Smart on the floor, the Celtics allowed 99.4 points per 100 possessions this season — two points better than their league-leading defensive rating — and that number rises by more than four points with him on the bench. He can defend four positions and was a nightmare for opposing guards.

The Celtics limped through a recent stretch of 11 games without Smart — after he nearly severed a tendon in the same hand by punching a picture frame — and were just starting to regain the form that led to 16 straight victories early in the season before half their rotation went down with ailments.

Horford will return from illness Friday night in Orlando, Irving is expected back as soon as Sunday, and Brown could clear concussion protocol early next week. But it was their depth that was beginning to make them so dangerous, with Smart and Terry Rozier wreaking havoc alongside Marcus Morris and Theis on the second unit, and they will now rely more heavily on Shane Larkin and Greg Monroe.

“Those guys have played big roles,” Ainge told the Sports Hub on Thursday. “Theis has had a fantastic year, as has Marcus Smart. He’s a big, big piece of our team. So, the next guy up has to step up.”

The Celtics will tighten the rotation in the playoffs. That means more minutes for Rozier and Morris off the bench and more minutes for Irving as a starter. “I think we just have to find a way,” added Ainge.

Boston no longer has a chance of catching the Toronto Raptors for the No. 1 seed, and it’s firmly entrenched at No. 2 — seven losses better than third-place Indiana. It can afford to rest the walking wounded in the regular season, but Smart’s absence is a game-changer for the playoffs. Without him, the Celtics are vulnerable against any of the eight playoff teams in the Eastern Conference.

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Ben Rohrbach is a writer for Yahoo Sports. Have a tip? Email him at rohrbach_ben@yahoo.com or follow him on Twitter! Follow @brohrbach

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