WASHINGTON -- Entering this season, the Mets thought highly enough of José Butto that they considered him a noteworthy piece of their organizational depth. If David Peterson and Tylor Megill were the Mets’ sixth and seventh starters, Butto had a credible case to be the eighth. Once José Quintana and Justin Verlander suffered injuries, Butto became the next line of defense.

But things did not work out as Butto, his coaches or the front office envisioned. Tapped for a series of spot starts in April and early May, Butto walked 11 batters in 12 innings, dampening any optimism the Mets might have gleaned from his 3.00 ERA over that stretch. Worse, Butto regressed in the Minors, producing a 7.39 ERA over his next 13 starts at Triple-A Syracuse as he struggled to adapt to the Automated Ball-Strike System.

Once a Top 12 prospect in the organization, Butto saw his stock fall while Joey Lucchesi, Denyi Reyes and others began receiving chances instead of him. Another spot start in August yielded poor results. Whatever grip Butto had left on a future role in the organization seemed to be slipping away, and fast.

Then came Wednesday’s game at Nationals Park, Butto’s first chance since his September call-up last week. From the jump, he looked like a different pitcher, appearing poised and -- more importantly -- in control of his pitches. The result was Butto’s finest start as a big leaguer: He took a shutout into the seventh inning of a walk-off, 3-2 loss to the Nationals, and might have emerged completely unscathed had Trevor Gott not allowed a pair of inherited runs to score.

“He was good,” manager Buck Showalter said of Butto. “I was looking at the balls-to-strikes, that’s about the only thing you could say negative about it. He stayed in attack mode. We were real proud of him.”

Although Butto did throw just 50 of his 81 pitches for strikes, he struck out six and walked only one. Butto allowed a baserunner in every inning but the sixth, yet, he didn’t stack together two in an inning until the seventh.

“The key was attacking the hitters, staying ahead always,” Butto said. “That [made] good results today.”

One start won’t convince the Mets to keep Butto in their future depth plans, but it should at least persuade them to give the rookie another start. With Carlos Carrasco done for the year after dropping a 50-pound weight on his finger, the Mets don’t currently have a fifth starter. They have little incentive to call up top prospect Mike Vasil, given the fact that they don’t need to protect him on the 40-man roster this winter. And while Lucchesi should draw at least a start or two down the stretch, there’s plenty of room for both to pitch with the Mets in full-on evaluation mode.

“We have options,” Showalter said. “It depends on what everybody wants to look at between now and the end of the year. … It’s important to look at guys in different roles, too -- whether it’s a Butto as a reliever, or Lucchesi or something. I’m not sure exactly what will end up happening, but there’s a lot of talk about it.”

Over the course of a season, most teams cycle through a dozen or more starting pitchers as attrition and injuries invariably hit. The teams with depth tend to weather 162 games better than those without it. Thus, it will be important for the Mets to enter this winter knowing which of their starters in unguaranteed roles -- Peterson, Megill, Lucchesi, Butto et al -- might be part of the solution, versus those who are better left in the Minors or out of the organization all together.

This September will offer the Mets a chance to evaluate them. Butto, for one, aced his first test.

“He certainly did what it takes to be strongly considered for [another start],” Showalter said. “It’s a what-have-you-done-for-me-lately world. It’s, ‘OK, can you do it again?’”