Andrew Stevenson is an option for the Nationals’ playoff bench. (Troy Taormina/USA Today)

Jayson Werth didn’t play in the Washington Nationals4-3 win over the Phillies on Thursday because of some shoulder tightness. The discomfort stems from getting hit by a pitch during his rehab assignment a couple of weeks ago and worsened in his first game back after missing nearly three months with a fractured foot. Werth, who is 0 for his last 20, insisted he would need two days off, max.

“I’ve been trying to battle through it and it’s playable, but I just haven’t been effective,” Werth said at his locker. “So I’d rather — especially with all those guys — get it right.”

“All those guys” to whom Werth referred are the outfielders on Washington’s roster. The group grew by three Thursday as the Nationals called up Andrew Stevenson, Rafael Bautista and top prospect Victor Robles. Stevenson and Bautista had been expected to join the club, but Robles’s promotion was a surprise. According to the team, the 20-year-old was summoned because Brian Goodwin suffered a setback in his recovery from a groin injury. There’s a strong chance he won’t return this season.

Goodwin was likely to have claimed a spot on Washington’s playoff roster as a backup outfielder — specifically a center fielder — after a solid season. The 26-year-old helped the Nationals overcome a few significant injuries in the outfield, batting .251 with an .811 OPS and 13 home runs in 74 games. Now the Nationals must figure out who will back up Michael A. Taylor in center field in the playoffs.

“We’ll see how it affects our outfield,” Nationals Manager Dusty Baker said. “Do we need speed? Do we need defense? Do we need a bat? You try to put all these things into the computer in your head and factor all the possibilities that I might need over the course of a game.”

Assuming Bryce Harper returns and the Nationals go with the standard eight-man bullpen for a best-of-five series, the Nationals’ projected playoff bench is Adam Lind, Howie Kendrick, Wilmer Difo, Jose Lobaton or Pedro Severino, and probably an outfielder capable of comfortably manning center.

Baker made one thing clear Thursday: Difo, a utility infielder who has played the outfield this season, won’t be on the postseason roster as a backup center fielder.

“Him being in the outfield, in September or in the playoffs, whatever, is kind of more of an emergency situation because the playoffs ain’t time to experiment,” Baker said. “Botched play, whatever it is, could ruin a kid if you have that over your head. … You try not to put him in that situation. I’d rather had a bona fide outfielder out there.”

The options for the last spot — if it goes to a player with experience in center field — are Stevenson, Bautista, Robles, and Alejandro De Aza. Stevenson, 23, is a plus defender, but has batted just .167 in 29 major league games. Bautista, 24, is one of the fastest players in Washington’s organization, but has just 13 career plate appearances. De Aza is experienced, but, at age 33, is a poor defender and not the hitter he was a few years ago. Robles is a five-tool talent, and one of baseball’s consensus top-10 prospects. But he also became the youngest player to play a game in the majors this season when he flew out to right field as a pinch-hitter in his major league debut Thursday.

“We got to see what we have,” Baker said. “I hear his youth is prone to mistakes, which you can’t make those mistakes in the postseason. It’s not fair to maybe put him in that situation.”

After Thursday’s win, the club has 22 games to figure it out. That’s 198 innings (assuming no extras) to split among eight outfielders — if you count Lind, a first baseman who’s played left field this season more than anybody could’ve expected, and Difo. That number would climb to nine if Harper returns from his bone bruise. On top of that, they’re trying to get Werth, when he returns, as many at-bats as possible without wearing him out down the stretch.

“There’s only so many innings,” Baker said, “and so many everything.”

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