CLEVELAND — The Boston Celtics won’t be announcing any lineup change for Game 4 of the Eastern Conference finals earlier than they need to. Asked on Sunday if he’s thinking about a lineup change, Celtics coach Brad Stevens played coy.

“I think you do that every day,” he said.

But you can be sure that Stevens has thought about it much more than usual in the wake of his team’s 30-point loss in Game 3. And you can be almost as sure that Aron Baynes will be in the Celtics starting lineup for Monday’s Game 4 (8:30 p.m. ET, ESPN).

Stevens has been willing to change his starting lineup all season. When the Celtics won 16 straight games in October and November, Baynes was in and out of the lineup, exchanging spots with Marcus Morris. Seemingly, the Baynes-Morris decision was based on matchups, with Baynes in the lineup against bigger, less mobile frontlines. But Stevens doesn’t put it like that.

“It’s all about trying to figure out if you can be successful offensively and defensively,” Stevens said of lineup decisions last week. “Sometimes you feel like you can be a little bit more successful on one end than the other, but both ends have to be taken into account.”

Through the first two rounds, the Cleveland Cavaliers had been more successful, especially offensively, playing small, with Kevin Love at center and, essentially, four shooters around LeBron James. Their most-used lineup – George Hill, J.R. Smith, Kyle Korver, James and Love – had scored 126 points per 100 possessions in its 110 minutes together. The Cavs started that way in Game 1 and the Celtics opened with Morris instead of Baynes (who started all five games of the conference semifinals) to match up.

Advantage: Boston. The Celtics led 20-7 before any substitutions were made in Game 1, which they won by 25.

In Game 2, Tristan Thompson was in and Korver was out. The Cavs still lost, but the start wasn’t so bad and the numbers when they played big vs. small were pretty good. Through two games, the Cavs had been outscored by 38 points and were a minus-7 in 29 minutes with a frontline of James, Love and Thompson. But Cleveland had outscored Boston, 31-18, in 12 minutes with James, Love and Thompson on the floor against Boston’s small frontline of Morris and Al Horford.

Just 12 minutes is a small sample size, but small sample sizes are all you get in a playoff series. And with the big vs. small success in mind, the Cavs started the same group in Game 3. Having won the first two games, the Celtics didn’t make any changes either.

Game 3 was a blowout and, essentially, nothing worked for the Celtics. But the Cavs’ big frontline was a problem again, particularly when the Celtics played small. Cleveland outscored Boston 22-8 in just nine minutes with James, Love, Thompson, Morris and Horford on the floor with no Celtics center (Baynes or Greg Monroe).

In playing big vs. small, the Cavs have been good on both ends of the floor. Thompson has made himself useful on offense as a screen-setter, as a roll man and as an offensive rebounder.

“He might not always score the basketball, but he’s going to get us extra possessions,” Love said of Thompson after Game 3. “He’s going to make the hustle plays, and he’s going to do a lot of stuff that might not necessarily show up in the box score.”

But the bigger difference compared to how the Cavs have played overall has been on defense, where Boston has scored just 26 points (on an effective field goal percentage of 33 percent) in the 21 minutes with James, Love, Thompson, Morris and Horford on the floor without a Boston center. Over 87 possessions with Thompson as his primary defender, Horford (the Celtics’ most efficient scorer in the postseason) has taken just six shots.

Does Baynes, averaging six points per game this season, fix that?

The Celtics have been better offensively with Baynes on the floor this series, but his presence doesn’t necessarily free Horford of Thompson, because the Cavs have been willing to defend Baynes with Love. And generally, Baynes’ value comes on defense.

In the regular season, Boston allowed just 97.0 points per 100 possessions with him on the floor. That was the lowest on-court DefRtg among players who averaged at least 15 minutes in 40 or more games. With Baynes and Horford on the floor together, the Celtics allowed just 95.0 points per 100 possessions, the lowest mark for any two-man combination in the league that played as many minutes as they did.

Assuming Baynes is the starting center on Monday with Horford at power forward and Terry Rozier at point guard, Stevens has a decision to make with the other two players on the floor, some combination of Morris, Jaylen Brown and Jayson Tatum. In the regular season, Morris came off the bench when Baynes started. Tatum has started all 95 games he’s played this season, while Brown has only come off the bench in Games 2-4 of the conference semifinals, when he was on a minutes limit after suffering a hamstring injury in Game 7 of the first round.

The Celtics have played just 31 minutes (regular season and playoffs) with Baynes, Horford, Brown and Morris on the floor without Tatum, and just 70 minutes with Baynes, Horford, Morris and Tatum on the floor without Brown.

But defending the Cavs begins with defending James, and that has been Morris’ job. He has been the primary defender on James for 101 of a possible 217 possessions in this series, with Brown (35) or Tatum (6) defending James for just 41 possessions total.

In each of the last four halves, with the Cavs playing big, Baynes has been the first sub for the Celtics (as early as two and a half minutes into the half). And he’s always replaced Tatum (three times) or Brown, but not Morris.

• Game 2, 1st quarter, 6:46 – Baynes for Tatum
• Game 2, 3rd quarter, 9:31 – Baynes for Tatum
• Game 3, 1st quarter, 7:18 – Baynes for Tatum
• Game 3, 3rd quarter, 8:57 – Baynes for Brown

Maybe, because Celtics have been switching most screens in this series, the initial defender on James isn’t as critical as it may seem. And the Brown-Tatum combination offers more offense, important given Baynes’ limitations on that end of the floor. Of course, the Celtics don’t switch with Baynes at center as much as they do with Horford at center.

Stevens was asked what would go into deciding who else would be on the floor if, hypothetically, Baynes was in the starting lineup. Would it be determined by the James matchup, by Morris’ comfort in coming off the bench or something else?

“There are two sides of the floor,” Stevens said, maybe downplaying the importance of who’s defending the best player in the world or perhaps just being coy again. “So there’s a lot that goes into it. We’ll make that decision based on both sides.”

Stay tuned.

John Schuhmann is a staff writer for NBA.com. You can e-mail him here, find his archive here and follow him on Twitter.

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