Who will Brad Stevens turn to without Marcus Smart?

Marcus Smart’s durability no longer appeared to be a concern after leading the Celtics in games played this year with 80 through Sunday night. For the first time in years, Boston looked poised to enter the postseason with a clean bill of health, something that would help to move past an underwhelming regular season.

Those hopes came to a close on Wednesday however after the team announced on Wednesday night that Smart would be sidelined from basketball activities for 4-6 weeks after suffering a partial avulsion of his left oblique abdominal muscle off of his iliac crest following a collision with Nikola Vucevic. The injury means Smart will be sidelined at the start of Boston’s postseason for the second straight year (he missed four games last year in the first round with a torn thumb tendon).

The 4-6 weeks timetable puts a possible return for Smart directly in the middle of a potential matchup with the Bucks in the Eastern Conference Semifinals. However, getting there in the first place will be a tougher obstacle than anticipated as Boston’s top defensive weapon watches the first round from the sidelines. Where exactly does Brad Stevens go from here? A look at the key questions in wake of a devasting blow to Boston’s playoff chances.

Who starts next to Kyrie?

A lot of this will depend on the specific matchups, so we will start here strictly by addressing the Pacers since that’s the series we know Smart will miss in its entirety. The Celtics have been vulnerable against elite backcourt and wing scorers and while Bojan Bogdanovic is no All-Star, he’s crafty enough to give a lot of the Celtics' wings problems. He's also Indiana's best scorer with Victor Oladipo sidelined. Smart’s job against the Pacers was shutting him down and he did that incredibly well in Indiana last Friday night during a blowout win (Bogdanovic scored three points). Jayson Tatum will also guard Bogdanovic in segments but he struggles with chasing crafty players on the perimeter at times. It's easier to get away with him on Wesley Matthews in the twilight of his career.

There are a couple of clear options here for the starting spot without Smart: Jaylen Brown and Gordon Hayward. Starting Brown brings a more athletic element in the starting five and reunites the group that saw success last season before Irving went down. Meanwhile, Hayward brings a smarter defensive IQ than Brown, making him more capable of handling Bogdanovic’s craftiness in spots, particularly going around screens. Hayward also provides another ballhandler in the starting five to take some pressure off of Irving, which Smart was also responsible for since his switch into the starting five.

The guess here is that Stevens rolls the dice with Brown to start, both for familiarity with that starting group and so he can leave Hayward to run the second unit offense. Brown’s presence will put a lot more pressure on Irving to run the show in the starting five and keep the ball moving, but it’s a better option than relying on Terry Rozier to play point guard for a couple of stints per night.

Who takes Smart’s minutes?

While either Brown or Hayward will get the starting nod, both of those guys were already expected to be playing big minutes on a normal night. Hayward seemed to be a lock for 30-plus based on his recent play, while Brown was a candidate for at least 20-25 minutes per night. It’s fair to guess that total can be turned up to 30-35 in the first round since Brown’s defensive versatility will be a necessity against a Pacers offense that is fairly reliant on its perimeter wings for its offense in Bogdanovic, Matthews, Tyreke Evans and Doug McDermott.

That leaves about 20-25 minutes from Smart's usual load to hand out on a nightly basis and it will be very interesting to see just where Stevens goes with those. It’s evident that Rozier will go from the fringe of the rotation to his usual regular season minutes load with Smart out of the picture, at least to start the series. The Celtics will be far better off using him as an off guard rather than let him run the bench offense but in situations where Irving and Hayward are resting at the same time (not many), Rozier will get his chance. That won’t be a good thing for this team on either end of the floor unless the reserve guard plays far better than he did during the regular season.

The other wildcard in play here will be Brad Wanamaker. He’s obviously not going to play big minutes but he is capable of running the point well, although ball pressure does tend to bother him (something Pacer point guards can bring). If the offense flounders with Rozier running the show, the guess here is Wanamaker gets a stint here or there so Stevens can buy a few minutes of rest for Irving and Hayward. Darren Collison will be too quick for Wanamaker to handle on the defensive end but he should be able to hold his own against Corey Joseph. To begin, though, I’d assume the Celtics rotation gets trimmed down to 8.5 players per night with Hayward, Morris and Rozier being the only sure things to play off the bench every night. Daniel Theis will be sprinkled in as well, particularly since the C’s will be committed to staying big more.

Will the Celtics get past the Pacers without him?

Yes, but it won’t be easy unless the supporting pieces on this team start to buy in more on the defensive end. The Pacers don’t have an offense that scares you but they run their sets methodically and creatively. The Celtics don’t have a lot of disrupters in their lineup and Smart’s absence is going to put a lot more pressure on Irving, Brown, Hayward, Tatum and Rozier on the defensive end. Without Smart, there will be one less player to clean up their mistakes, communicate well and sacrifice their body in almost any situation. There is also potential offensive upside that comes with more minutes for Brown, Hayward and Tatum but Hayward is the only one among that group that can run an offense. The Celtics will need to be careful to avoid going into iso mode without Smart sharing the wealth and navigating the pick-and-roll. More of those duties will fall on Hayward now.

Given the fact that defense has been the bigger issue for this group all season, the pressure on Brad Stevens will rise to try to cover up for Smart’s absence on that end. The answer may be sticking with big lineups even more to ensure rim protection since the numbers have been far better with two true bigs at the helm. Irving, Brown and Rozier will be tested all series long going around pick-and-rolls and the Pacers will punish them for their mistakes. They all need to be engaged and far better in that department than they showed during the regular season.

With that said, there still isn’t enough talent in Indiana to overtake Boston here. The Celtics have the offensive horses to outrun them and barring a defensive collapse, it’s hard to fathom Indy mustering enough offense to win four games.

From there, the waiting game will continue with Smart heading into a potential second-round series. The Celtics already created a brutal road for themselves this regular season and one more injury in a meaningless Game No. 81 will put the pressure on everyone in this group. Everyone in the rotation has wanted opportunities and Stevens has no choice now but to place some faith in guys who haven’t necessarily earned it as the postseason begins.