PITTSBURGH — For James McDonald, success is all about the numbers zero and one.

As long as the zero comes first.

Throwing the first pitch for a strike has proven quite beneficial to the 27-year-old Pirates’ right-hander.

“You miss with that first pitch, the hitter pretty much knows a fastball is coming next,” McDonald said. “You get ahead in the count right away, it’s a guessing game.

“Fastball, curve, change, slider ... He has no idea what’s coming. That plays to any pitcher’s advantage.”

Particularly to McDonald, who has command of just about every ball that leaves his hand these days.

“He’s been efficient with his fastball and is showing good command of his breaking stuff,” Pirates manager Clint Hurdle said. “That’s a good package he’s put together.”

McDonald’s numbers have been off the charts of late.

His earned run average in the month of May was 1.54 over five starts. Only the Giants’ Ryan Vogelsong (1.51) had a lower ERA among National League starters for the month.

McDonald allowed just 23 hits in 35 innings pitched in May. He permitted six earned runs, struck out 39 and walked eight.

Entering Sunday’s scheduled start in Milwaukee, McDonald is 4-2 with a 2.20 ERA, 63 strikeouts and 19 walks in 65.1 innings pitched. He was 9-9 with a 4.21 ERA in 31 starts last year.

“Last year in late April, we had people wondering how many more starts we were gonna give him,” Hurdle said, smiling.

The talent has been there for McDonald, who worked out of the bullpen for the Los Angeles Dodgers in 2009 after being named their Minor League Pitcher of the Year in 2008. He came to the Pirates along with minor league outfielder Andrew Lambo for veteran reliever Octavio Dotel at the 2010 trade deadline.

“When I first came here, all I heard about McDonald was he was a guy who couldn’t get over the hump,” first-year Pirate catcher Rod Barajas said. “I haven’t seen any hump this guy’s struggling with.

“His stuff has been electric.”

McDonald scattered five hits in eight scoreless innings against division-leading Cincinnati in his last start. He allowed four hits each to the New York Mets, Washington and Houston in his three starts prior to that.

McDonald took a no-hitter into the seventh inning against Colorado on April 25 at PNC Park.

“I used to think too much on the mound, worry about every situation,” he said. “Now I don’t care about anything when I’m out there.

“My job is to get hitters out. I get the sign, work with the catcher and make my pitches. I’ve simplified everything.”

The Pirates are hovering around .500 because of their pitchers and McDonald has been as good as any of them.

He shrugs off the .500 record and prefers to look toward the future. The Pirates were in first place last July, only to lose 46 of their last 67 games.

“We’d like to ride the momentum all the way to September this time,” McDonald said.

Hurdle concurs.

“We’re heading in the right direction,” the manager said. “I’ve played for and managed a team that was nowhere near first place on Memorial Day and wound up in the World Series.

“There’s a long way to go, but I like our direction, I like our focus and I like our attitude.”