With the starting pitchers turning in solid performances and the offense clicking, the Post Sports Live crew looks at whether the Nationals' road trip to San Francisco and St. Louis will be a good barometer for the team's status as a contender. (Post Sports Live/The Washington Post)

From the dugout steps during games, Washington Nationals pitching coach Steve McCatty has perhaps the best perspective on what has propelled the team’s improvement over the past month. The Nationals’ starting pitching, the backbone of the team’s success over the past few seasons, has solved its early-season inconsistencies and been — by some measures — the best in baseball since mid-May.

In one recent historic 56-inning span that stretched from June 4 to June 11, Nationals starters combined to strike out an absurd 54 batters and walk one. The rotation, once ranked in the middle of the pack in the majors, has risen to the top thanks to stout pitching from Stephen Strasburg, Jordan Zimmermann, Doug Fister and Tanner Roark and pushed the Nationals closer to the top of the National League East.

The numbers elicit nothing but a smile and shrug from McCatty, who isn’t surprised.

“They’re that good,” McCatty said. “Obviously pitching to a one-something ERA, 50-some strikeouts and one walk is not going to happen all the time. But they have the ability to do it.”

Over the past 30 days, the Nationals’ starting rotation has posted a major league-best 2.64 ERA. By the advanced metric called Fielding Independent Pitching, which attempts to take a team’s defense out of the equation, the Nationals’ mark of 3.14 in that span is tied with the St. Louis Cardinals for the best in baseball. And that has been without Gio Gonzalez, who returns from the disabled list Wednesday after a month of dealing with left shoulder inflammation.

“It’s been awesome,” Zimmermann said. “Guys are going up and throwing strikes and pounding the zone. Good things are going to happen when you do that. And it’s going to be great to finally be at full strength. Having [Gonzalez] back and having a lefty in our rotation is going to be helpful. We’re excited to have him back.”

When Gonzalez landed on the disabled list May 18, the Nationals’ starting rotation ranked 19th in the majors with a 3.99 ERA. Since then, Strasburg has a 2.50 ERA over 392 / 3 innings, Zimmermann has punched up a 2.36 ERA over 42 innings, Roark has posted a 1.85 ERA over 34 innings and Fister has a 2.58 ERA in 381 / 3 innings. Blake Treinen, who filled in for Gonzalez, posted a 3.24 ERA over three starts. Because of those dominant stretches, the Nationals’ rotation now ranks fifth in the majors with a 3.34 ERA and first with a 3.28 FIP.

“They’ve all done a better job of keeping the ball down, and few pitches have been up,” catcher Wilson Ramos said. “For me, that’s the biggest key for them. And you can see the results they’ve had since.”

According to FanGraphs.com, Nationals starters have thrown the most first-pitch strikes (64.4 percent of the time) in baseball. Just three starting rotations — the Miami Marlins, Cardinals and Oakland Athletics — have thrown more strikes than the Nationals (47.4 percent). Washington’s rotation leads baseball with a 3.84-1 strikeout-walk ratio.

For the first six weeks of the season, however, the Nationals’ rotation was inconsistent, often putting the team in early deficits, which strained the bullpen and offense. For reasons McCatty can’t explain, each starter’s command issues coincided, and their improvements now have, too. Although better control is the collective reason, each starter has different explanations.

Strasburg made a small tweak in how he stood on the pitching mound — planting his right foot in front of the rubber instead of half on it — and it helped to stabilize his delivery and control. He also eliminated a new pitch this season, his slider, which opponents were hitting .455 against.

“He’s been able to throw the three other pitches and focus on spotting his fastball better,” McCatty said.

Roark said settling into a groove of pitching every five days has helped; five of his 13 starts this season have been on longer than regular rest. His heightened focus on each pitch and growing confidence in his instincts also have helped.

Roark is “throwing what I want and not just shake yes to the catcher,” he said. “It’s the pitch I want to throw in my head that matters. If you throw and have a certain pitch you want to throw in your mind and you put something else, the execution isn’t there.”

The biggest difference for Zimmermann has been finding his slider again. In April, opponents hit .320 off his slider, according to BrooksBaseball.net. Zimmermann felt his front shoulder jerking out earlier than normal in his delivery, and the pitch was mostly flat. “It was garbage,” he said.

Zimmermann said he did nothing out of the ordinary to regain the feel for his slider, no messing with grips or delivery. The pitch simply returned to form. In May, opponents’ average off the slider dropped to .250 and then .100 in June. The pitch helped him toss perhaps the best game in Nationals history, a 12-strikeout, two-hit, no-walk shutout of the San Diego Padres on June 8.

“I just kept throwing it and finally got a good feel,” Zimmermann said. “It’s a big pitch for me and a pitch I need to be successful. When I wasn’t going good, I obviously didn’t have my slider. That was one of the big keys. If I had that thing figured out, I was going to be fine. And it’s been great the last couple starts.”

“It’s kind of funny that when his slider did come back that consistently he’s been more able and comfortable in locating his fastball and keeping it down,” McCatty added.

The return of veteran groundball starter Fister (3.08 in eight starts) from a spring training lat strain also has helped power the Nationals’ surge. Improved defense — the Nationals haven’t made an error in a season-high nine straight games and have turned more balls in play into outs — is also a factor. And more runs from the offense has eased pressure on the starters.

“As a starting pitcher, it already takes a load off your shoulders,” Gonzalez said. “You go out there with a comfortable lead and just pound the strike zone and do what you can. At the beginning of the season, it was a little rough. But the team has finally clicked together, and it shows.”