Celtics took it to the undermanned Lakers from the start, and that’s a good sign

LOS ANGELES — The Celtics are finding that they make their lives so much easier when they come out of the starting gate focused and prepared.

Such was the case Thursday night at Staples Center, when they jumped the Lakers early, racing to a 14-2 lead and leading the rest of the way for a 121-113 win, their fifth straight.

Far too often this season, the Celtics have started games meticulously or with a porous stretch that creates a big deficit. And while they have had the fortitude to rally, it often has resulted in defeat.

Against the Lakers, Jaylen Brown was simply magnificent with 40 points, and his teammates whipped the ball around the floor to get the best shot.

The Lakers aren’t themselves right now. They have been decimated by injuries, with LeBron James and Anthony Davis on the bench Thursday dressed casually, as they recover from theirs.

But this was a game the Celtics had to win, the easiest matchup of their three out West. Perhaps if it were earlier this season, the Celtics don’t come out focused and end up in a real tussle with an inferior opponent. This time, that wasn’t the case.

The Celtics never trailed, and it became hairy only when coach Brad Stevens thought a 27-point lead was safe and inserted the end of his bench, which allowed a 22-2 run (more on that later).

But the best part about this win, one that thrust the Celtics into a tie for fourth place in the Eastern Conference, was the prowess of Brown, who was 17 of 20 from the floor, including an admirable halfcourt heave to end the third quarter.

Brown’s April has been as impressive as Jayson Tatum’s. Brown is averaging 24.8 points and 7.0 rebounds per game, and shooting 44.8 percent on 3-pointers. The most encouraging aspect of this recent stretch is that Tatum and Brown have reasserted themselves at the perfect time.

“Just wanted to come out and be aggressive,” said Brown. “Celtics-Lakers is a matchup that kids dream about. Regardless of who’s on the floor, I’m excited to play. The energy having those Lakers fans back in the arena, we just wanted to go out and get a win.”

The Celtics are finally approaching full health. Evan Fournier is the only regular who remains out, and it’s uncertain when he will return from COVID-19 protocol. The regularity and familiarity of the past few weeks has been the primary reason for the resurgence.

It was a relief for Stevens that the Celtics surrounded Brown with balanced scoring but also got the ball in his hands on a night when he was nearly flawless. Five other Celtics scored in double figures.

The only detriment in the blowout win was turnovers. The Celtics committed 21, keeping the Lakers in the game until an early fourth-quarter run extended the lead to 27. Stevens decided then that the starters were done for the night; Tatum and Marcus Smart did not play in the fourth quarter and Brown scored two buckets in the opening minutes before leaving at the 9:13 mark.

A pressing concern all season has the lack of depth on the bench. The third-team reserves couldn’t score, and then couldn’t defend as the Lakers went on that 22-2 run to slice the deficit to 7 with 1:50 left, forcing Stevens to reinsert his starters.

The lead shrunk to 5 before Brown added two buckets to seal it. But the performance of the quintet of Tremont Waters, Carsen Edwards, Aaron Nesmith, Moe Wagner, and Semi Ojeleye altered what should have been an abbreviated night for the starters and a stress-free flight back to Boston.

The Celtics will have to assess whether they can trust any of those players to contribute down the stretch. They can get away with going nine or 10 deep, especially when Fournier and Robert Williams (who missed Thursday with knee soreness) return. But that stretch could be even more evidence that president of basketball operations Danny Ainge needs to retool his bench in the offseason.

And Celtics faithful were again uttering the name of Isaiah Thomas as an option after he was not signed to a second 10-day contract by the Pelicans this week.

The hope is that the Celtics’ top 10 players are jelling so well that the final seven won’t see the floor much.

The past three games were an example of the Celtics’ potential when they are focused and totally engaged. Except for a shaky first half against the Nuggets last Sunday, the Celtics played three strong games, relying on their stars but also getting key contributions and performances from the complements.

The Celtics are not an Eastern Conference contender yet, but they are trending in the right direction.

Gary Washburn is a Globe columnist. He can be reached at gary.washburn@globe.com. Follow him @GwashburnGlobe.