The Nationals are moving Mitchell Parker to the bullpen for the remainder of the season, a reflection both of the left-hander’s year-long struggles and the recent emergence of rookie Andrew Alvarez in the rotation.

Parker, whose 16 losses and 5.85 ERA both rank last in the majors, was informed of the switch earlier this week and said he understands the club’s rationale, even though he’s never pitched in relief before.

“Obviously, this year hasn’t been ideal,” he said. “And really, it is what it is. Roles change, goals stay the same. Still got to pitch, still got to get guys out, still trying to win ballgames.”

In spite of his struggles, Parker had held onto his starting job for months, with no viable alternatives knocking on the door in the Nats’ farm system. But when MacKenzie Gore landed on the 15-day injured list in late-August with a minor shoulder issue, the club promoted Alvarez from Triple-A Rochester and then watched the left-hander deliver a 1.15 ERA over his first three big league starts.

Gore’s return to the active roster last week left the Nationals with six healthy starters, but they stuck with the extra man knowing they’d need him to get through Tuesday’s day-night doubleheader against the Braves. Now that they’ve reached the season’s final stretch, with nine remaining games over the next 10 days, they decided there was no need to use a six-man rotation.

With Alvarez (who starts tonight against the Mets) earning the opportunity to keep pitching in the majors, Parker became the odd man out.

“We want to see Alvarez start a few more games with us,” interim manager Miguel Cairo said. “He’s been doing a good job, and we just want to see him pitch a little bit more. Mitchell threw, I think, 30 starts in the big leagues … going to the bullpen might be a little different, but it will give a chance for him to throw a little less and to help us.”

A fifth-round pick in 2020, Parker was a surprise organizational win last season, going 7-10 with a 4.29 ERA in 29 starts as a rookie. And he began this season in impressive fashion, going 3-1 with a 1.39 ERA through his first five starts.

But things took a decided turn downhill from there, and over his last 25 outings, Parker has gone 5-15 with a 7.00 ERA. That includes eight starts in which he’s surrendered six or more runs, matching Patrick Corbin for the single-season club record.

Asked today what he believes has been the biggest difference between his performance this season compared to last season, Parker simply pointed to the bottom line.

“Not keeping us in close ballgames,” he said. “It’s hard to win when you’re spotting the other team a couple runs every night. It sucks, but it’s baseball. It is what it is.”

Parker will finish out the season in the bullpen, but it hasn’t been decided yet how he’ll be used in 2026. With the Nationals still needing to name a permanent head of baseball operations and manager, that decision could ultimately be made by people who aren’t currently working for the organization.

But with MacKenzie Gore, Cade Cavalli, Brad Lord and Josiah Gray (scheduled to make his final rehab start tonight for Triple-A Rochester) all higher on the current depth chart, Parker would probably find himself competing with Alvarez and Jake Irvin (8-13, 5.76 ERA) for what could be only one open slot in the Opening Day rotation.