Arizona Diamondbacks starting pitchers on an early roll

SAN DIEGO – Shelby Miller didn’t know the answer to the question – what team’s starting rotation had the best ERA in the National League? – but he figured it out right away, and he smiled and nodded when he did.

“Is it us?” he asked. “Nice.”

The Diamondbacks are 15 games into their season, early enough that one bad start could skew the numbers drastically. But their starting pitchers entered Wednesday with a 3.28 ERA, a hair better than the St. Louis Cardinals for the best mark in the league. Compare that to last season, when the rotation’s ERA of 5.38 was the second-worst in the National League through 15 games.

“I think we’re a very talented group,” Diamondbacks left-hander Patrick Corbin said. “I think we have five really good pitchers who every day are going to go out there and keep us in games. Everybody is feeling good. The ball is coming out well. And guys are, I think, pitching deeper into games and keeping us in ballgames.”

Most around the game wouldn’t consider the rotation’s success to be a major surprise. Each of the Diamondbacks’ five starters is good enough, generally speaking, to have a spot in the rotation of just about every team in the league. And each is accomplished at the big-league level in his own way.

But they all entered the year needing to demonstrate some degree of improvement off of last season. So far, at least, each of them has, although they’ve made only three starts apiece. And they all still have room for improvement.

The biggest jump has come from Miller, who struggled so badly during his first season with the Diamondbacks that they sent him to Triple-A at the All-Star break. This season, he has turned in three competitive outings, including a 7 1/3-inning, one-run performance on Tuesday night. His stuff is vastly improved from where it was a year ago.

“He’s definitely confident,” pitching coach Mike Butcher said. “He’s in a really good place. I know I keep saying the same thing, but he’s in a really good place mentally, physically, emotionally. (Tuesday night) was a big night for him to go out there and pitch well. It was just really good to see.”

Corbin has a 2.81 ERA and has thrown six innings twice. Taijuan Walker, who has six walks and 16 strikeouts in 16 innings, is coming off his best start, giving up just one run in five innings against the Dodgers, an outing that might have lasted longer if not for back tightness.

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Right-hander Zack Greinke, who started Wednesday night, was coming off a bad outing against the Dodgers but had pitched competitively in each of his other two. Lefty Robbie Ray’s results (1.96 ERA) have been great, though he has battled control issues (a league-leading 12 walks).

Corbin says multiple factors could be involved with the staff’s across-the-board improvement, everything from pitchers’ arms feeling better and producing better stuff; to better pregame information from the club’s analytics department and pitching strategist Dan Haren; to the benefit of a fresh start after last season.

“All of that helps,” Corbin said. “I think it definitely helped, too, getting off to a better start this season where guys go out there and can build off the last start. I really think that helps when you see someone else go out there (and throw well).”

Said Ray: “It’s a credit to our offseason work and putting last year behind us and moving forward. I think that’s the biggest thing, just realizing this year is a new year. We always knew we had a good rotation, it’s just about putting it all together.”

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The starters have managed to have success despite a defense behind them that has been shaky at times. The Diamondbacks have committed a league-worst 14 errors, and they rank second-to-last in the NL in defensive runs saved.

In addition to leading the league in ERA, the rotation is tied for the second-fewest home runs allowed and ranks fourth in strikeouts. There are, of course, some areas that could stand to improve, including the walk category, in which the Diamondbacks lead the league, though improvement from Ray alone would help there.

“Our team as a whole is playing good baseball and we’re all kind of vibing off of each other,” Miller said. “I think right now there’s a lot of things going on that are positive, and it’s all kind of falling into place. With our starters’ potential and how we’re pitching, we know we’re capable of it. It’s just about doing it more than anything.”

Reach Piecoro at (602) 444-8680 or [email protected]. Follow him on Twitter @nickpiecoro.

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Thursday’s game

Diamondbacks at Padres

When: 6:10 p.m.

Where: Petco Park, San Diego.

Pitchers: Diamondbacks LHP Patrick Corbin (1-2, 2.81) vs. Padres LHP Clayton Richard (1-2, 3.60).

TV/Radio: FSAZ/KMVP-FM (98.7), KHOV-FM (105.1).

Corbin was in trouble throughout much of his start last week at Dodger Stadium, but he managed to navigate his way through six innings, giving up five runs (three earned). … He has just seven strikeouts and seven walks in 16 innings. … Corbin logged 13 2/3 innings against the Padres last season, posting a 3.95 ERA with six walks and 14 strikeouts. … Richard tossed eight scoreless innings against the Dodgers in his first start of the season but has allowed four earned runs over six innings in each of the past two. … Richard, who split last season between the Cubs and Padres, faced the Diamondbacks three times and had solid results, posting a 3.24 ERA in 16 2/3 innings. … Richard has a three-pitch mix, with a fastball around 90 mph, a slider and a change-up.

Coming up

Friday: At Chase Field, 6:40 p.m., Diamondbacks RHP Taijuan Walker (2-1, 3.94) vs. Dodgers LHP Alex Wood (1-0, 1.00).

Saturday: At Chase Field, 5:10 p.m., Diamondbacks LHP Robbie Ray (1-0, 1.96) vs. Dodgers RHP Kenta Maeda (1-1, 7.07).

Sunday: At Chase Field, 1:10 p.m., Diamondbacks RHP Shelby Miller (2-1,3.50) vs. Dodgers RHP Brandon McCarthy (2-0, 2.12).