The Boston Celtics looked very much on track to seal the deal in the 2024 NBA Finals after taking a 3-0 series lead against the Dallas Mavericks. While the Mavericks have mounted a few runs here and there to threaten to keep the series close, the Celtics have had an answer for every question Dallas has asked of them. But in Game 4, with the Mavericks' backs against the wall, the Celtics were thoroughly outplayed on both ends of the floor. It got so bad during the Celtics' 122-84 loss that they decided to wave the white flag and throw their bench players in with 3:18 left in the third quarter.

Make no mistake about it, the Celtics remain very much in control of the series. A 3-1 series lead is still a healthy one, especially when the Finals is heading back to the friendly confines of TD Garden. There is a level of desperation that teams down 0-3 in a series have that the Celtics simply weren't able to match on Friday night, but they will have at least three more cracks at sealing the deal, beginning on Monday night.

Nevertheless, there is mild cause for concern for the Celtics after the Mavericks were able to exploit a few holes en route to a 38-point demolition. In the playoffs, blowouts like these may not usually carry over from game to game, but the Celtics have to get it together quickly before the Mavs get any ideas of a historic comeback.

Celtics' offense sputters as the Mavericks dig deep on defense

Usually, when an offense falters like the Celtics' did on Friday, the star players are at fault. This certainly was the case in Game 4. Jayson Tatum and Jaylen Brown could not get anything going, although that's more of a testament to the Mavericks' defense on the night rather than some questionable shot selection.

For instance, Tatum got to the paint a few times but he missed three good looks in the shaded area. Meanwhile, Brown missed four point-blank shots at the rim that he usually has made throughout this playoff run. Those shots, more often than not, will go in. But the Mavericks emphasized being more on point with their defensive rotations that they didn't allow too many clean looks at the basket for most of Game 4.

A big point of discussion throughout the series has been the defense of Luka Doncic. The Celtics have targeted Doncic relentlessly on switches and have feasted as a result. Doncic has allowed a staggeringly high percentage of blow-bys, forcing the Mavericks defense to collapse and making them choose between getting destroyed in the paint or allowing open threes.

Doncic has been guilty of poor positioning off the ball, as well as lapses in concentration; he fouled out in Game 3, which helped the Celtics hold off the hard-charging Mavericks during their spirited comeback in the fourth quarter. But in Game 4, the Celtics faced an entirely different version of Doncic.

Still the main target of the Celtics' offensive scheme, Luka Doncic didn't just survive on defense, he thrived. Guarding everyone from Tatum to Brown to Jrue Holiday, Derrick White, and Al Horford — the Mavericks star kept in stride with ballhandlers, was diligent in getting in proper help position, and he was very active in poking the ball loose from ballhandlers.

The Celtics see red whenever Luka Doncic is on the floor, and they turn into raging bulls every time the Mavericks star switches onto the ballhandler. In Game 4, the matador decided to fight back against the bull. In the end, Doncic being rock-solid on defense caused the Celtics offense to struggle, as the other Mavericks defenders did not have to overcompensate to cover for a weak link on that end of the floor.

The Celtics' starters combined to shoot 14-41 from the field and they turned the ball over a total of 11 times. That simply won't cut it in a closeout game against a desperate Mavericks team.

It's Luka Doncic's turn to feast on switches

It may seem unfair to single out any single player as the sole reason for the Celtics' meh defense in Game 4. But the Sam Hauser minutes did not help matters at all even though he played his heart out on defense.

With Jayson Tatum picking up a few fouls, the Celtics had to play Hauser some serious minutes. The Mavericks proceeded to seek Hauser out on nearly every single possession, and Luka Doncic, as a result, got almost everything he wanted on offense as the game got out of hand for the Celtics in the second quarter.

Doncic is too big and too strong for Hauser to deal with in the post, and the Mavericks star did not settle for difficult looks. He chiseled his way into the paint against Hauser, and even when the Celtics put Jrue Holiday or Jaylen Brown on him, Doncic still found a way to get close to the hoop and create an easy shot, whether a clean look from up close or an open jumpshot for his teammate.

This paint-scoring dominance from Doncic (he made seven buckets from five feet or closer) then collapsed the Celtics' defense on multiple occasions. They had to overreact and send some early help, which paved the way for some timely threes that added to the Mavericks' lead in the first half, a deficit that the Celtics weren't able to recover from.

Just to put in perspective how much the Celtics' defense struggled, it was Xavier Tillman Sr. who did the best job guarding Luka Doncic on the night. Could more Tillman minutes be in store for Game 5, especially with Al Horford doing nothing on either end of the floor on Friday night? Horford may be a beloved veteran, but he struggled in his 23 minutes on the court.

Horford was a non-factor in protecting the rim, and he was very much absent on the glass. He didn't make up for it by making threes (he made just one) as the Mavericks prevented him from getting up some shots in the first place as the Celtics struggled to create open looks all night long. Horford has to be better if he were to win his first NBA championship, especially amid Kristaps Porzingis' weird injury situation.