Adam Eaton grabs at his knee Friday night. The Nationals center fielder will be lost for the season thanks to a torn ACL suffered on the play. (Mitchell Layton/Getty Images)

Adam Eaton will miss the rest of the 2017 season with a torn anterior cruciate ligament in his left knee, a person familiar with the situation confirmed Saturday. Eaton injured the knee lunging for first base in Friday night’s loss to the New York Mets, a fluke play that now leaves the Washington Nationals without the leadoff man and center fielder for whom they surrendered three top prospects this winter.

Eaton was hitting .297 at the time of his injury, but he served a purpose beyond statistics for a deep and experienced lineup that did not need above-and-beyond production. The 28-year-old emerged as a spark at the top of the Nationals’ order, good enough in the leadoff spot to allow Trea Turner to hit second and the Nationals to alternate lefty-righty-lefty through the top and heart of their lineup. He also provided a relentless energy, the kind of edge and hustle with which Nationals General Manager Mike Rizzo has tried to infuse the roster over the past two years. Fox Sports first reported the news of Eaton’s diagnosis.

Adding to the blow is the fact that the Nationals’ deal for Eaton was one of the most discussed (read: “criticized”) deals of the offseason, and the Nationals traded prized pitching depth for five years of Eaton at a below-market price. Now they will get four years plus a month of Eaton at that price, assuming he returns at full strength, which is never a given with injuries this severe.

Meanwhile, the Nationals will give Michael A. Taylor everyday duty in center field, according to a person familiar with their thinking. This will be Taylor’s third chance at regular duty, and perhaps his last, as he is arbitration-eligible after this season and has yet to prove he can sustain success at the major league level. When Denard Span got hurt in spring training of 2015, Taylor hit .229 over 138 games.

When Ben Revere was injured on Opening Day 2016, Taylor hit .231 in 76 games, which prompted the Nationals to put Turner in center field instead. But opposing scouts continue to consider Taylor, 26, one of the best defenders in the Nationals’ system, which happens to be well-stocked with defensive-minded outfielders. Among center fielders who have played at least 800 innings in center field since 2015, Taylor ranks 12th in UZR (Ultimate Zone Rating), ahead of stars Mookie Betts and Mike Trout, for what that is worth.

Should Taylor flounder, the Nationals already called up speedy outfielder Rafael Bautista for center field depth. Their first pick in the 2015 draft, Andrew Stevenson, is hitting well at Class AA Harrisburg and could be due for a promotion soon. Victor Robles, the presumptive center fielder of the future, is on the disabled list at Class A Potomac.

Eaton, meanwhile, will have to focus on 2018, the final year in which Bryce Harper and Daniel Murphy (among others) are guaranteed to be on the Nationals’ roster. His game relies heavily on speed and hustle, both of which will be affected by the injury to his knee, regardless of how well it heals. The injury calls his offensive and defensive future into question. The Nationals have not announced a timetable for his return, though torn ACLs normally require at least six months, and often more. Former Nationals catcher Wilson Ramos, for example, tore his ACL in late September and has not yet returned to baseball action.

So the Nationals will have to move on without Eaton, their impressive lineup deflated, their edge diminished in his absence. They will likely be able to fill his void defensively, with Taylor or one of the speedy young outfielders in their system. Offensively, they will miss his pesky left-handed at-bats and speed at the top of the order. Turner will lead off in his stead, and while Taylor hit second Saturday, he seems unlikely to do so long-term. The Nationals will have to find someone to replace Eaton at the top of their order, but will likely have a hard time replacing his grit, which they might not see again until next February in West Palm Beach, Fla.