Cole Henry’s impressive rookie season has come to an unfortunate and premature end.

The Nationals placed Henry on the 15-day injured list this morning with a back strain, bringing an abrupt halt to the reliever’s first big league season with exactly 15 days remaining on the schedule.

Orlando Ribalta, who had just been optioned to Triple-A Rochester three days ago to clear a spot for MacKenzie Gore’s return from the IL, was recalled and will be back in the bullpen for today’s series finale against the Pirates.

Henry struggled during a high-leverage appearance Saturday afternoon. Entrusted with the top of the eighth with the Nats leading 1-0, he walked two of the three batters he faced, throwing only seven of his 18 pitches for strikes before getting pulled in favor of left-hander PJ Poulin, who allowed both inherited runners to score during what became a four-run rally for Pittsburgh.

It was Henry’s third consecutive shaky outing. He gave up three runs (two earned) on two hits, a hit-by-pitch and a wild pitch Monday in Miami, then returned to the mound two nights later and walked two during a scoreless inning.

Saturday’s appearance brought the 26-year-old’s ERA up to 4.27, where it will remain through season’s end, a tough break in what had been an impressive rookie campaign.

The Nationals’ second-round pick in 2020 from LSU, Henry was a highly touted prospect who was supposed to become part of the organization’s rotation at some point. But a shoulder injury halted his progression through the farm system in 2022 and he wound up having thoracic outlet surgery, a potential career-killer.

After totaling only 49 2/3 minor league innings in 2023-24, Henry was given an opportunity to come to big league camp this spring as a reliever. He fully embraced the switch and wound up reaping the benefits of it.

Though he didn’t make the Opening Day roster, Henry was called up from Triple-A two weeks into the season and made his major league debut April 13. Through his first 20 games, he sported a 2.01 ERA and earned his way into a high-leverage role at the back end of the bullpen.

Henry’s second-half performance was more erratic, but he was given the opportunity to record his first two career saves when interim manager Miguel Cairo played matchups and used closer Jose A. Ferrer in the eighth.

All told, Henry ends his season with a 4.27 ERA, 1.424 WHIP, two saves, 52 strikeouts in 52 2/3 innings and 57 appearances, avoiding any arm injuries.