Nationals reliever Kelvin Herrera is unable to snag Maikel Franco’s eighth-inning single up the middle that scored Scott Kingery. (Jonathan Newton/The Washington Post)

The reason Erick Fedde took a loss Saturday afternoon was that he had pitched so well, his manager thought he deserved a chance to push himself. The margin by which Fedde became a loser Saturday was the minuscule space between Spencer Kieboom’s glove and Maikel Franco’s foot as it crossed home plate — a space so tiny it took officials in New York 2 minutes 20 seconds of replay review to determine there was any space at all.

Franco scored that go-ahead run on a sacrifice fly in the seventh inning, a play upheld after review. The Phillies added two runs against Kelvin Herrera in the eighth, and the Nationals fell, 5-3. They are 1½ games behind the Phillies for second in the National League East. As with many strong starts for this team recently, Fedde’s most promising big league outing was not enough. The Nationals (40-35) have lost seven of nine and scored two runs or fewer in five of them.

“I repeat myself every day, but it’s about the little things,” Manager Dave Martinez said. “Today was about the little things. Not knocking balls down. The plays at home. Things like that.”

As Fedde threw in the bullpen this past week, Max Scherzer leaned against the wall behind him. They put a bag of balls near the outside corner, and Fedde tried to throw his slider down into the bag, to establish the bite.

“Max would be like, ‘That’s what we’re looking for!’ ” Fedde said. “ ‘Now do it again.’ ”

Some within the organization see some Scherzer in Fedde, mostly in his competitiveness. Fedde thinks the comparisons apply most to repertoire. Scherzer throws five pitches, three breaking balls — slider, curve and cutter. Fedde is trying to learn to do the same, at a far younger age than Scherzer mastered his arsenal. Occasionally, Fedde’s cutter starts to look too much like his slider and vice versa. His change-up is a work in progress. He’s being tutored by the best.

Fedde (0-3) is a few months older than Aaron Nola (9-2), the young Phillies right-hander who finally appears to have made the leap from prospect to star and held the Nationals to two runs on four hits in six innings. On a less experienced and successful team, Fedde might have gotten a couple of years to work through growing pains as Nola has in Philadelphia. The Nationals have not been able to let young pitchers such as Fedde use big league innings to get their big league bearings. With Stephen Strasburg out, this is Fedde’s chance, and he seems to be seizing it.

“He’s getting confidence every time he goes out there, and I love it,” Martinez said. “He’s keeping us in the ballgame, and I can’t say enough about what he did today.”

Fedde applied Scherzer’s lessons. He was confident enough in the cutter to throw the pitch to Phillies slugger Rhys Hoskins in a full count in the first. He mixed it with a slider that was a few mph slower, just like Scherzer suggested. He landed his curveball for strikes and was able to mix and match pitches called by rookie catcher Spencer Kieboom.

“You guys are watching it, “Kieboom said. “He’s been getting better and better every single time.”

Before the game, Kieboom sat at his locker with Strasburg, talking about Phillies hitters the injured right-hander knows well by now. If there is an advantage to having so many veterans on the disabled list, it is that youngsters such as Fedde, Kieboom and Juan Soto can benefit from their experience in real time. Soto doesn’t seem to need much help. He hit another opposite-field double with two outs in the first, then scored on Daniel Murphy’s two-run, two-out single. Fedde needed more help than that.

For all of Scherzer’s tutelage, Fedde also stuck to what makes him great Saturday — a sinking fastball that touched 96 mph and hovered around 95, got weak contact, and found its way onto Twitter highlight reels that called it “nasty,” among other things. The only runs the Phillies (41-33) scored came when they strung four pieces of well-placed weak contact together to score two runs, just missing outstretched gloves.

“I felt like my stuff was pretty good today,” Fedde said. “I had a lot of groundballs today. That’s usually when I know my stuff’s good.”

By the end of the sixth, Fedde had thrown 97 pitches and kept his team in the game against Nola, enough to convince some managers to end his day there and preserve the good feelings. Martinez decided to test him.

“It was the bottom of the order. He was just throwing 93, 94,” Martinez said. “It’s time to stretch him out a little bit, and he was dealing.”

Fedde surrendered a leadoff double to Franco, and Martinez pulled him. Ryan Madson did not surrender another hit, but the shallow flyball to Eaton was enough to score the run. Eaton’s throw beat Franco. Kieboom’s tag could not, a play he and his manager agreed he misplayed by fielding the throw too far up the line to get back to the base.

Because that run scored, Fedde’s line included three runs on eight hits, two walks and three strikeouts. He did enough to give the Nationals a chance to win and the hope that he might start doing so regularly now. They need to start seizing those chances. They have let plenty of them slip away.