PHILADELPHIA — DJ LeMahieu may be the least demonstrative individual on the Yankees’ roster; the next time he thumps his chest publicly will likely be the first. But the authentic celebration in their dugout after his third career grand slam said more than he ever would.

In the midst of a season clouded by the veteran’s injuries and underperformance, LeMahieu enjoyed one of the brightest days of his career, driving in six runs as the Yankees completed a three-game sweep of the Phillies with a 6-5 victory at Citizens Bank Park.

“DJ was huge. Everybody in here loves him,” said outfielder Alex Verdugo. “He goes about his business the right way; true professional, great teammate. That’s somebody that we’re always going to root for. That’s somebody that’s been such a great player for so many years that you know it’s always in there for him.”

Not much has gone as expected this year for LeMahieu, whose spring was interrupted by a right foot fracture. He entered play with a .173/.264/.216 slash line (38 OPS+) in 47 games, and he recently lost his starting job at third base to Jazz Chisholm Jr., who had never played the position before Monday.

Yet Yankees manager Aaron Boone said LeMahieu will remain in the infield mix. He has frequently served as a defensive replacement behind rookie first baseman Ben Rice, a converted catcher, and Boone gave LeMahieu a starting nod on Wednesday with left-hander Cristopher Sánchez on the mound.

LeMahieu rewarded that decision with a second-inning grand slam, a blast to left-center field that was initially ruled a double and overturned by review. There were hoots and hollers in the Bombers’ dugout; standing at second base while the umpires huddled, LeMahieu even cracked a smile.

“It’s been a tough go for me, but today felt good,” LeMahieu said. “My teammates have my back in supporting me. To come through and see how excited they are, it’s a good feeling for sure.”

Said Yankees starter Nestor Cortes: “You look at the list of guys that go into an MLB clubhouse and are ready to perform, it’s DJ, right there at the top. It doesn’t surprise me that he’s going to find it. He’s going to turn it on for us and be a really big factor for us.”

While LeMahieu said he’d prefer to be in the lineup, his time on the bench has permitted him to make minor adjustments offensively, which he believes paid off in Wednesday’s contest.

“It’s one good game, but it definitely felt good,” LeMahieu said. “I feel like I’m on to something, and I feel like I’m in a good spot.”

Boone said that “there is absolutely still an important role” on this team for LeMahieu, who is under contract for two more seasons after 2024. LeMahieu added a two-run double in the sixth inning to support Cortes, who has had his own issues of late.

It has been a difficult stretch for Cortes, who heard his name discussed in trade rumors. One report had him going to the Cardinals if the Yankees had imported another starting pitcher, though Cortes said that he is not sure how much truth there was to that.

“It was all speculation,” Cortes said. “My name being thrown around, I feel like there was nothing concrete about it. I was just ready to make my start today, and that’s what I worked for. Hopefully, I can put up a string of good starts going forward.”

The Yankees had not won Cortes’ previous six starts, but he retired the first nine batters he faced on Wednesday, holding the Phils to three runs in 5 1/3 innings, including a Weston Wilson homer.

Luke Weaver and Mark Leiter Jr. allowed one run each, giving closer Clay Holmes a one-run lead to protect. The Yankees have been firmly in Holmes’ corner despite eight blown saves, the most recent of which came on Tuesday.

Holmes finished the job this time, surviving an Austin Hays fly ball to the warning track in left field before inducing Bryce Harper to hit into a game-ending double play. Yankees hurlers held Harper hitless in 13 at-bats during the series.

“You always want to get back out there and help the team win,” Holmes said. “That’s when you’re at your best, when you’re just competing. It was nice to come back out today after being picked up last night, secure this win and get the sweep.”