“Maybe it’s just playing the game for the third year,” said Bellinger, who won the N.L. Rookie of the Year Award in 2017. “I never really had problems with lefties. Last year was just a season for me to make adjustments — making some wrong adjustments. I’m just playing the game that I know how to play.”

This season the Dodgers have a new hitting coach, Robert Van Scoyoc , who has helped the team set an N.L. record for home runs, led by Bellinger’s 44. Chris Taylor, an infielder and outfielder, said that Bellinger seemed to be tinkering less with his swing this season and that he understood Bellinger’s drive to escape a platoon.

“Especially at this level, all players have a little bit of an ego, and everybody believes they’re everyday guys,” Taylor said. “It’s hard on a player; we can take it personal when we don’t face righties or lefties. You just have to try to look at the big picture and realize we have so many good players on this team that it’s not so much a detriment to you, it’s more about giving everybody a shot. That’s the strength of our team.”

When you hit .400, as Bellinger did through May 21, you make a compelling case to play every day. Bellinger — the son of Clay Bellinger, a former Yankees utility player — said he knew that pace was unsustainable, and his average now stands at .306. He is hitting .227 since Aug. 21.

“There’s been an adjustment this last month where I think teams are crowding him more,” Roberts said. “He’s just got to continue to stay in the strike zone, because as you get to playing playoff teams and in the postseason, they’re going to pitch around him. You have to really be stubborn in the strike zone, and it’s going to challenge Cody from here on out.”

Even with the recent slump, Bellinger has reached base in 18 of his last 19 games and led the N.L. in wins above replacement through Thursday (as calculated by Baseball Reference), with 8.2, one more than Milwaukee’s Christian Yelich, the reigning N.L. M.V.P. whose season ended on Tuesday when he broke his kneecap on a foul ball.

Only Yelich and Washington’s Anthony Rendon had a higher O.P.S. than Bellinger’s 1.041 through Thursday. Bellinger’s overall value gets a boost from his defense, which is the best on his team. He has made 88 starts in right field but has started the last 10 games at either first base or center field.