The Philadelphia Phillies have relied heavily on outfielder Brandon Marsh during a stunning turnaround in the standings this season, with the first-time All-Star providing steady defense in the outfield and flashes of impressive offensive production throughout the season.

But as October approaches, every lineup decision becomes more significant, especially against elite pitching. And it seems that pressure has pushed manager Don Mattingly to move the breakout star back into a reduced role as he suddenly regresses toward his career averages.

Philadelphia Phillies Move Brandon Marsh Back Into Platoon Role As All-Star Surge Fades

During the Phillies’ recent series against the Los Angeles Dodgers, Mattingly acknowledged that Marsh's resurgent struggles against left-handed pitching have forced the coaching staff to consider him as a liability against southpaws.

On Wednesday, when the lineup revealed that Marsh would be benched against Dodgers pitcher Eric Lauer, a beat reporter discovered that the outfielder is once again reduced to a platoon role.

“I asked Mattingly if this is just a day off for Brandon Marsh, or the start of a platoon,” On Pattison’s Anthony SanFilippo reported. “He said he has been thinking about the platoon ‘because the numbers haven't been great against lefties. I've liked some of his (at-bats) early, but that seems to have been a battle as we went on.’”

The comments suggest Marsh has been placed back into the platoon role he played for most of his Phillies tenure, despite his first-half breakout as one of the best contact hitters in the sport. Now, the Phillies could begin shielding him from left-handed starters as they attempt to maximize every lineup advantage down the stretch.

Philadelphia Phillies’ All-Star Brandon Marsh Sees Struggles Return

The underlying numbers explain why the Phillies are at least exploring a platoon arrangement.

“Marsh has struggled somewhat against lefties in recent weeks; in his last 24 plate appearances against lefties before Tuesday, Marsh had just two hits, with 13 strikeouts and one walk,” The Athletic’s Charlotte Varnes reported. “Against (Justin) Wrobleski, the Dodgers’ lefty starter (on Tuesday), Marsh struck out twice but also flied out to center field at 101.2 mph, among his hardest-hit balls against lefties all year.”

That combination of poor results and encouraging contact illustrates why the Phillies have a difficult decision to make on Marsh. There could still be reason to believe he’s able to keep up his production against left-handed pitchers, though Mattingly seems set on platooning him after his move this week.

For a Phillies club with World Series aspirations, maximizing production in every lineup spot could outweigh sticking with everyday roles, even for a breakout All-Star like Marsh.