PHILADELPHIA -- Kyle Schwarber said everything changed on Friday night when he dropped a ball in left-center field, just two pitches into the first inning at Citizens Bank Park.

“I feel like if I catch that ball, it’s a different ballgame,” Schwarber said following the Phillies’ 5-3 loss to the Red Sox. “Wheels was going.”

Phils ace Zack Wheeler had an opportunity to stop the club’s losing streak at four games in the series opener against Boston. The right-hander has stopped plenty of losing streaks over his previous three-plus seasons in Philadelphia.

But Wheeler allowed five runs (four earned) in 5 1/3 innings as the Phillies lost their fifth straight game to fall to 15-18.

“I kind of pride myself in coming in and shutting that down,” Wheeler said about the losing streak. “It’s frustrating. That’s probably the most frustrating thing out of today. I wasn’t able to stop that.”

The Phillies have been outscored during the losing streak, 45-17. Philadelphia starters have a 9.53 ERA, allowing 24 earned runs in 22 2/3 innings. No starter has allowed fewer than four runs: Bailey Falter on Sunday in Houston (four runs, 4 1/3 innings), Taijuan Walker on Monday in Los Angeles (eight runs in 3 1/3 innings), Matt Strahm on Tuesday (four runs, 3 1/3 innings), Aaron Nola on Wednesday (four runs in 6 1/3 innings) and then Wheeler on Friday.

Wheeler (3-2, 4.26 ERA) and Nola (2-2, 4.64 ERA) have been unable to find their footing through the season’s first 33 games. They have made seven turns through the rotation at this point. They have had quality starts together in just two of those turns.

Boston scored an unearned run in the first inning to take a 1-0 lead. Raimel Tapia hit a fly ball to left-center field to start the game. Schwarber and center fielder Dalton Guthrie converged. Schwarber said he called it first, but he dropped the ball.

“It hit my glove,” he said. “It has to stay in my glove.”

Tapia scored on a two-out single from Rafael Devers. Wheeler allowed four earned runs the rest of the way.

“That just wasn’t a good game for me,” Wheeler said. “I was pulling a lot of fastballs, something was just a little off. I couldn’t pinpoint what it was. I threw some good offspeed pitches today, probably some of the best I’ve thrown all year, but my fastball command was off. I couldn’t sink it in to righties. I was pulling the four-seamer a good bit, too.

“It’s a little harder when you don’t have your command.”

The Phillies tied the game in the fourth, when they scored three runs. Bryce Harper, who played in his first home game since Game 5 of the 2022 World Series, got things started with an infield single. The Phils had runners on first and second with one out in the ninth, but Schwarber and Trea Turner each struck out swinging to end the game.

Home-plate umpire Doug Eddings called a 2-1 pitch a strike to Schwarber, although it was off the plate. It evened the count, instead of pushing it to 3-1. Schwarber struck out swinging three pitches later on a slider.

That’s the way things are going lately for Schwarber and the Phillies. Schwarber, who went 0-for-5 with three strikeouts, is batting .183 with a .697 OPS.

“I’m going to keep working,” Schwarber said. “I’ve just got to keep working in the cage. I feel like the cage is kind of the biggest thing and it’s going to set the table, if you just go out there and compete. … I feel like we were playing some pretty good baseball, then obviously got to L.A., got to flush that series.

“If you take away my mistake [in the first inning], I feel like we’re playing a pretty good baseball game there.”