Erick Fedde tossed five shutout innings Thursday. (Joe Robbins/Getty Images)

WEST PALM BEACH, Fla. — As Erick Fedde threw five shutout innings against the Mets’ regulars Thursday, Dusty Baker liked two things in particular. One, he liked that Fedde was aggressive with his fastball, something the prospect was not when the Marlins roughed him up in his last outing. Two, he liked that Fedde implemented tips pitching coach Mike Maddux gave him about his tempo, a sign that he is able to learn quickly and adjust to new challenges.

“You like his aptitude, that’s what you like probably more than anything,” Baker said. ” … That’s what you like to see out of young players. He pays attention. He doesn’t say much, but you see he’s always paying attention.”

Fedde put forth a great deal with his performance Thursday, in which he allowed two hits and zero walks while striking out three Mets in the Nationals’ 1-0 win. He showed that he can handle a major league lineup, though all the spring training caveats apply. He showed that he can extricate himself from jams, striking out Curtis Granderson and inducing a groundball from Neil Walker to escape a one-out, two-on situation in the fourth. Mostly, however, he showed that he can bounce back, because after he allowed five earned runs in 1 2/3 innings in his last start, he dominated Thursday.

“I think my biggest problem last game was not attacking and falling behind. That’s what I did this time,” Fedde said. “I told myself no matter what, I’m going to attack the guys, and whatever happens, happens.”

Whatever happens, happens is pretty much the state of things for Fedde. He probably will not get another start in major league camp, because the Nationals have all their starters back, and are locking in their schedule. He finished last season in Class AA Harrisburg, and could start this season there, too. But after an impressive spring in which he pitched to a 3.29 ERA over five appearances, Fedde could also be ready for Class AAA Syracuse — and perhaps to make an appearance in the big leagues by September.

“He was close when he got here, so who knows what’s going to happen injury-wise or whatever,” Baker said. “He’s one of the guys at the very top of the list in case something happens, or just through natural progression of pitching.”

Fedde joins A.J. Cole and Austin Voth as young pitchers the Nationals could call for a spot start if needed, and Cole has filled that role before. The Nationals have shown a willingness to pull pitchers from as low as Class AA, which is where they grabbed Joe Ross two seasons ago, and Lucas Giolito last year. Cole and Voth have more Class AAA experience than Fedde, and therefore might be the more obvious choices to fill in if injuries strike. But they had more experience than Giolito and Reynaldo Lopez last year, too. The Nationals were willing to take a chance on an unproven rookie, and probably will be again.

So as it stands, whether Fedde gets another start or not, the 2014 first-round choice made an impression in his first major league camp. Now the Nationals’ top pitching prospect, he seems likely to be ready sooner than later.

Notes

— Right-hander Joe Nathan, whose deal with the Nationals includes a March 24 opt-out date, pitched for the second straight day Thursday, his first official back-to-back appearances of the spring. After he allowed two earned runs in 1 1/3 innings Wednesday, Nathan faced one batter Thursday, Yoenis Cespedes, and struck him out.

As things stand, the Nationals do not seem to have room for the 42-year-old former closer in a bullpen so jam-packed it might have to survive without a long man if the Nationals decide they cannot afford to carry one. Nathan seems unlikely to bump any of the younger, harder-throwing candidates like Koda Glover or Enny Romero, the latter of who is out of options and would likely be lost if not on the Opening Day roster.

“I can’t say right now [what will happen with Joe],” Baker said. “We’re still trying to sort through the numbers. Joe wasn’t that good the other day in the first inning, but he was great the next inning. Today he came in to get a very tough Cespedes here today. That shows the resiliency of his arm, for him to go back-to-back days like that. … We’ve got some very tough decisions to make.”

— Romero, meanwhile, pitched another scoreless inning Thursday and has not allowed a run in five spring appearances with the Nationals and two appearances for the Dominican Republic in the WBC. The 26-year-old’s trouble has always been command of his high-90s fastball, but so far this spring, he has controlled it well. In 7 2/3 innings between the Nationals and Dominican team, Romero has walked one batter and struck out seven.

“The thing I like about him is he has shown he can throw his breaking ball 3-2 or behind in the count to get them off his fastball,” Baker said. “It’s my understanding they had taken that pitch almost away from him in his last stop. So his ability to do that, his confidence level is high, I think that the WBC really helped him to control the nerves.”