SAN FRANCISCO — By the second inning Tuesday night, Rob Thomson fielded a lineup that included Edmundo Sosa, Otto Kemp, Dylan Moore and Rafael Marchán. It was not how the Phillies envisioned it; Alec Bohm had a sore groin and J.T. Realmuto took a foul ball to the ankle. But some of it was by design. They were facing a lefty, Robbie Ray, and that meant an adjusted lineup.

The best way to describe the 6-0 loss to the San Francisco Giants: It was a game that happened. Two weeks into this season, the club’s most evident weaknesses appear whenever they face a lefty. It’s not just Kemp or Sosa, who are platoon players deployed only when a lefty pitches. The Phillies, as a team, have hit .138/.242/.213 against left-handed starters.

That .455 OPS ranks 29th in the majors so far.

“I mean, obviously, we have to get better,” Phillies manager Rob Thomson said.

The Phillies are 6-5, and they’ve lost all four games started by a lefty. They did win two games started by a lefty opener, but that’s in part because those pitchers went an inning or less.

Bryce Harper is 1-for-11 against lefty starters. Trea Turner is 2-for-11. Bohm is 0-for-7 and Adolis García is 1-for-8. Those are the two middle-of-the-order righties who should thrive against left-handed pitching. With Bohm out, García batted cleanup for the first time as a Phillie. He was held hitless, although he did throw out a runner at home plate from right field.

Last season, the Phillies had a .723 OPS against lefty starters. That ranked 12th in the majors. But they were 23-25 in games started by lefties, marking their first season with a losing record in those games since 2021. It was not a strength.

Opponents will always think about putting lefties on the Phillies in an attempt to neutralize Harper and Kyle Schwarber. But they’ve had relative success in those situations. The Phillies’ whole plan in these games relies on Turner, Bohm, Sosa, and Kemp. All four of them had an OPS better than .800 against lefty starters in 2025.

They have sputtered to begin 2026. The Phillies have four extra-base hits in 87 plate appearances against lefty starters. The lone one off Ray was a hard-hit Sosa double to begin the second inning. But Marchán and Kemp struck out looking, Moore flied out to center field and Sosa was stranded at second. The Phillies did not put another runner in scoring position until the seventh inning.

Their only home run this season against a lefty starter? It came from Marchán, the backup catcher.

Marchán will play again on Wednesday because Realmuto will need some rest for his bruised right foot. Thomson said X-rays were negative, but Realmuto was hurting. It takes a lot to force him out of a game. For now, the team believed Realmuto had avoided any serious injury.

The rest of the night, after Realmuto departed, was sloppy. Turner booted a sure double-play ball in the fifth inning. Two batters later, Matt Chapman blasted a liner to deep left. It was the hardest-hit ball of the game. And Kemp froze.

He took a step to he left, then twisted back to the right. He jumped, but the ball sailed over his head. It went as a run-scoring double, but it’s a ball that would have been caught by a left fielder with any experience. It prolonged the inning and led to another Giants run. The Phillies handed San Francisco six outs in that inning.

“In hindsight, I wish I would have tried to beat the ball to the spot,” Kemp said. “Better chance to make that play rather than try to time a jump up. It’s another play that I can learn from. Just try and keep it in the back of my mind, and know that when the ball’s hit hard like that, just try to beat it to the spot.”

It’s at least the third ball Kemp has misplayed in 26 innings as a left fielder this season. He is an infielder who is learning the outfield on the fly because the Phillies believe he is an asset in the lineup whenever a lefty pitches against them. Kemp is 1-for-11 with six strikeouts this season.

“Trying to stay sharp as much as I can,” Kemp said. “… A little bit of a challenge, but we’ll be all right. It’s still early. I feel good about where we’re at. I think we’re on the right track and we’ll get to where we need to be.”

If Kemp is a liability on defense, there is greater pressure to contribute at the plate whenever he plays. Thomson has defended Kemp, who is just a small piece of this whole thing. He batted seventh on Tuesday. The Phillies like the idea of Kemp, an undrafted and self-made player who defied odds to reach the majors. Is Thomson worried about Kemp’s confidence at a new position?

“Um, no,” Thomson said. “He’s a pretty stable guy.”

It’ll be a bit before Kemp starts again. The Phillies are not scheduled to face another lefty starter until, possibly, a week from now. There is work to do for every right-handed hitter in the lineup.

“Get back to the basics, you know?” Thomson said. “Try not to do too much. Stay in the middle of the diamond. And get good pitches to hit.”