Brandon Marsh on his 4-for-37 start for the Phillies: ‘I’m letting my guys down’

ST. LOUIS — For more than a half hour after Sunday’s game ended, Brandon Marsh sat in a chair in front of his locker in full uniform, weighed down by a season-opening slump.

“I know I’m not doing my part, which stinks the worst,” he said after going 0-for-3 with two strikeouts in the Phillies’ 7-0 loss to the Cardinals. “I just feel like I’m letting my guys down, and I need to be better for them.”

Marsh is 4-for-37 with 14 strikeouts to begin the season. Among Phillies regulars, his .439 OPS ranks second-lowest to only Alec Bohm (.331).

» READ MORE: Phillies’ Alec Bohm addresses early-season slump: ‘The game’s trying to teach me a lesson’

But after committing in spring training to finally giving Marsh a chance to play every day, against lefties as well as righties, manager Rob Thomson hasn’t ditched the plan. With the Phillies facing a lefty starter for only the second time in 10 games Sunday, Thomson sat Bryson Stott and Max Kepler but kept Marsh in the lineup.

Thomson’s patience will last only so long.

Asked if he would keep sticking with Marsh, Thomson left open the possibility of making a change in the outfield.

“I’ve got to think about that one,” Thomson said. “Because he’s really frustrated — and understandably."

Marsh’s fifth-inning at-bat against Cardinals lefty Matthew Liberatore was especially noncompetitive. He struck out on three pitches, including back-to-back sliders that were away from him and outside the strike zone.

“Like I said, just going through it right now,” Marsh said. “I’ve got to do anything I can to help this ballclub win, and right now, I’m not doing that. So, I’ve got to figure some things out.”

The Phillies could give Johan Rojas more playing time in center field as an alternative to Marsh. They could also use reserve infielder Edmundo Sosa in left field against lefties, although he’s still learning the outfield on the fly. Help may be on the way when righty-hitting utilityman Weston Wilson comes off the injured list after straining a muscle in his side in spring training.

» READ MORE: Phillies’ ‘10th man’ Edmundo Sosa does whatever it takes to get in the lineup. It’s been that way since he was 15.

Touted center-field prospect Justin Crawford is waiting in the wings. The Phillies challenged the 21-year-old with a roster spot in triple A, and he’s off to a .254 start with a .641 OPS.

In choosing to play Marsh over fellow left-handed hitters Kepler and Stott against Liberatore, Thomson noted before the game that none has hit lefties yet this season. Small sample alert: Stott has hit in 16 at-bats against left-handed pitchers so far; Kepler is only 3-for-15 against them.

“None of those lefties really at this point — I’m not trying to be negative — are swinging the bat very good against lefties,” Thomson said. “So, I figured we’ll put the best defense out there.”

Instead, Marsh only added to his early-season frustration.

After catching a fly ball down the right-field line Saturday, Nick Castellanos got a high five from a young Phillies fan in the front row.

But Castellanos lingered for a fist bump.

“Just to give him a little bit more love,” he said.

Castellanos got his wish, then reciprocated by tossing the ball to the fan. A clip of the catch — and Castellanos’ interaction with the boy, who was wearing a powder blue Mike Schmidt jersey — circulated on social media.

“We’re all out here having a good time,” Castellanos said.

Ranger Suárez (back) is scheduled for four innings and/or 55 pitches Tuesday night for low-A Clearwater in his second minor league start. The Phillies want to get him to the 100-pitch range before reinstating him from the injured list. ... Top prospect Andrew Painter is lined up for three innings and/or 50 pitches Friday night for Clearwater. ... With a first-inning walk, Kyle Schwarber extended his on-base streak to 21 games dating to last season. ... With the NCAA hockey championship being held in St. Louis on Saturday night, president of baseball operations Dave Dombrowski was able to attend the game and watch his alma mater, Western Michigan, win the title. ... The Phillies will return home to open a four-game series against the Giants. Taijuan Walker (1-0, 0.00 ERA) will be opposed by righty Landen Roupp (0-1, 3.60) at 6:45 p.m. Monday.