When a team has to make a lineup change in Game 6 of a playoff series to keep their season alive, you'd usually point and laugh at them. The Celtics going back to their double-big lineup against the Sixers was a slightly different proposition — this group had fueled a run to the Finals for Boston last season, even if there were reasons to be skeptical of their value in this lineup.

"We expected it today, we worked on it all morning," Doc Rivers said of the lineup change prior to the game. 

Evidently, they didn't work on enough. The Sixers played their worst offensive game of the season, scoring just 86 points at a pace of 90.5 points per 100 possessions. Philadelphia's defense was stout, forcing 17 Celtics turnovers and propping up the team for basically the entire night. But in the end, their inability to punish the Celtics for shaking things up was their doom. They are heading back to Boston for a Game 7 on the road, as dire of a situation as you can face in the NBA.

So what's the path forward from here?

How bad was it vs. double bigs?

Real bad. Hide your eyes unless you want to see the truth.

The Sixers managed to score just 80 points per 100 possessions when Boston had both bigs on the floor. And it's not all that difficult to see why. This was the sort of look Joel Embiid was seeing with Al Horford and Robert Williams III on the floor at the same time, with his paths to the basket blocked and no immediately obvious passing options.

Doc Rivers' explanation for their struggles after the game came down to a couple of broad concepts, ball movement and sharing the basketball (which are really more like the same concept).

"I thought there were plenty of opportunities to swing, catch, get Joel the ball in the right spots on the elbow, and we just didn't do it," Rivers said. "I'll watch the film and I'll give you a better answer tomorrow, but I didn't think we trusted. It didn't matter what lineup, we didn't score in any lineup tonight, we struggled scoring."

There's definitely something to that lack of sharing when you watch guys like Tobias Harris fly in for overly aggressive (and ultimately harmless) attempts from eight feet and in, so locked in on the rim they failed to notice anything else around them. The Sixers were so consumed by trying to deliver a knockout blow that they missed the forest for the trees at times.

But Embiid certainly wasn't the only player impacted by Boston's change in personnel. Tyrese Maxey was one of the few Sixers players to drape himself in glory, but it took him some time to find his footing as he tried to combat the length Boston showed around the basket. Putting him in an action with Joel Embiid meant Maxey had to try to get through two different bigs to do so, with Horford sitting in drop and Williams lurking as a roamer. Again, look at the options in front of him, keeping in mind Williams would block his runner attempt soon after:

There was plenty that won't show up in the stat sheet, possessions where the Sixers looked to have a slight advantage only to lose it quickly. 

What personnel could change

The biggest card Doc Rivers played in the second half of Game 6 was removing P.J. Tucker for Georges Niang. As James Harden would say in an extended answer after the game, basketball isn't hard. Sometimes you just have to replace the guy who can't make shots with the guy who scares teams even when he isn't.

"We'll put [Tucker] on the floor more when there's one big, we'll put Georges or Melton on the floor when there's two," Rivers said after the game. Simple enough.

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The value of that approach was obvious just based on how the Celtics lined up their guys when Niang was subbed in. Robert Williams moved out of the corner and onto Joel Embiid, with Horford chasing Tobias Harris around. That left Marcus Smart and Jayson Tatum as the low men for Boston, with each of those guys offering much less in the form of rim protection than Williams. And even with Horford trying to cheat off Harris, the very first possession ended with an easy Embiid catch in the lane, moving right into a quick jumper.

The second possession with Niang on the floor in Tucker's place was even more telling. With Williams overly concerned about trying to get back to Embiid and expecting a teammate to rotate behind him, the Celtics' big man quite literally jumped out of James Harden's way on his path to the basket, and Harden scored a layup plus a foul with no one there to contest.

Even if the Celtics rotate behind WIlliams, Harden has a quick pass to Niang in the corner for a great look, providing Philly with a great option in both scenarios. As it was, it was a rare moment of success for Harden the scorer on a night where he looked mostly helpless — this was Harden's only basket of the entire second half. His explanation for his struggles after the game did not exactly inspire confidence heading into a hostile environment for Game 7...

...but he often faced the same wall of Celtics defenders that we saw against Embiid and Maxey up top. 

This dynamic makes Rivers' lineup choices a gigantic subplot heading into the game, because there is risk on both sides of the coin. Tucker might just throw up bricks for four quarters and empower the Celtics to shut you down, which will inspire a few calls to put Niang in to start the game and blow up what the Celtics have going. But Niang is very likely to have a worse defensive game than he did at home in Philly, squandering some of the advantages you gain via the shooting. Who will win the chess match?

The ideal option would be to plug De'Anthony Melton into that spot, getting shooting without sacrificing defensive toughness. There's one problem with that.

Just make shots?

It was Melton, not Tucker, who ended up being the face of Philadelphia's shooting problem on Thursday. Melton finished the game 0/5 from the field and 0/4 from three, with three of those misses from downtown coming in the fourth quarter.

The first of Melton's fourth-quarter misses was if you want to be generous) a slightly difficult shot, but only because Melton turned it into a stepback jumper instead of rising and firing on the catch. The two misses afterward were about as clean as you're going to get in the fourth quarter of a tight playoff series:

You would love to say that he could simply make these in Game 7, but it's hard to go into a Game 7 on the road and bank on getting much of anything from role players. And this is where Rivers' suggestion that they needed to share the basketball more falls a bit flat. These are open looks shot by a guy who was a reliable outside threat for Philadelphia all season, on plays where the Sixers didn't fight against the current and trusted Melton to make something happen.

"Off the top of my head, we had a lot of open shots that we just didn't make, and they made a couple more," James Harden said Thursday. "We can make those shots, and it's a different ballgame. It's pretty simple."

Speaking of open shots — Harden could have helped blow open the double-big lineup early in the game, when Embiid was getting double and triple-teamed and he was passed open for a shot of this quality:

And Maxey would airball a shot with a little over three minutes to play in the game, with Jaylen Brown not reasonably close enough to bother Maxey on the release.

So maybe these start to go down in Boston on Sunday, and suddenly we're right back where we found ourselves in the middle of the series, with Philadelphia mostly setting the tone and controlling the style of the series. But not everything is as simple as "shoot the Celtics out of this lineup."

What the heck happened in crunch time?

It should be emphasized here that the Sixers were still winning this game with under five minutes to play, and that bringing Niang into the game had spooked the Celtics out of going to the Horford/Williams frontcourt. What followed was a series of simply horrendous offensive possessions, with the Sixers either settling for terrible shots, playing too slow, or managing both at the same time.

While the Sixers are a slower team by nature, they toggled into "prevent offense" too early and too often in the fourth quarter, walking the basketball up the floor and settling for tough shots for no real reason. Up 83-81, the Sixers took 10 seconds off the shot clock before the ball touched Embiid's hands to get into a set, resulting in a stepback jumper for Harden that had no chance of going in.

Speaking of shots that had no chance, this felt like a fitting capper for Philadelphia's night:

All night long, Harden seemed more concerned with the whistle he couldn't get rather than attacking with gusto, culminating in this moment, where he screamed at the officials after going down without much of a case to draw a foul. His feet getting tangled up with Smart was unfortunate, but there's no obvious trip, and Harden's choice to flail and throw the ball to nowhere was just that: a choice.

It's what made his comments about the officiating so concerning. On so many of the plays where he hoped to get a whistle, replays showed marginal contact at best. And in a series that has featured Harden beating up Horford in space during their wins, the Sixers failed to punish the Celtics for showing a big to their lead guard in any style of coverage, drops or switches or otherwise. There was very little downhill momentum created by Harden, and Philadelphia's offense looked stuck in the mud as a result.

Joel Embiid's explanation for their crunch-time woes was short and sweet.

"I think it was three things. We had a lot of wide-open shots, we didn't make them. We stopped moving the ball. And I don't think I touched the ball the last four minutes of the game," Embiid said. "Missed a lot of good looks, I didn't touch the ball at all."

The Sixers might win a road Game 7 even if their role players are subpar again, but it will require Harden to play like he's in a basketball game and not a foul-drawing event, and for Embiid to find the ball when it matters most. 

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