The Associated Press Pirates pitcher Bailey Falter delivers against the New York Mets last Saturday at PNC Park in Pittsburgh.

PITTSBURGH — Bailey Falter has a had a breakthrough season for the Pittsburgh Pirates this year, and the 28-year-old left-hander is quick to ascertain the primary reason for his success.

The addition of a change-up to his pitching repertoire has been a game-changer for Falter, who has a 6-3 record with a 3.62 earned run average over 17 starts this season.

“I live in Mesa, Arizona, and I switched up my training at a facility where I work out there in the offseason,” Falter was saying earlier this week during the Pirates’ recent homestand at PNC Park. “Probably a lot of the key to my success this year has to do with the usage of my change-up.

“I never really used to throw a change-up, but this year — I don’t know the exact number — I’m probably throwing it at least 10 percent of the time,” added Falter, who has struck out 52 batters and walked 32 in 87 innings pitched this season.

The Pirates hired 76-year-old Brent Strom, a former Major League Baseball left-handed pitching veteran, as their assistant pitching coach last offseason, and Strom worked with Falter on developing the change-up.

“Brent Strom, our assistant pitching coach, lives in Tucson, Ariz, about a two to two-and-a-half hour drive from my home in Mesa, and he came in last offseason to watch me throw several of my bullpen sessions last offseason,” Falter said. “He was very invested with me last offseason, and he just thought that (throwing the change-up) would open a lot of doors and create a lot of opportunities for me.

“I talked to him about it and I kind of got a little bit more familiar with the grip on the pitch,” Falter added. “Then I talked it over further with (Pirates pitching coach) Oscar (Marin), and I feel like I’ve been having some pretty good success with it this year.”

Indeed.

Falter has been giving the Pirates steady outings in most of his appearances this season, and he enjoyed an historic, record-setting May. During that month, Falter carded a miniscule ERA of 0.76 — a Pirates franchise record in a single month for pitchers in the live ball era (1920 on) making at least six starts in the month.

Falter gave up just three extra-base hits during his stellar May, which included three scoreless outings in three Pirates victories — a seven-inning, four-hit effort against the Cincinnati Reds, a 6•-inning, two-hit performance against the San Diego Padres and a six-inning, two-hit outing against the Atlanta Braves.

“Everything was just firing on all cylinders,” the 6-foot-4, 205-pound Falter said about his historic month. “I think that my mechanics were in a really good spot, and my arm, my body and everything else felt really good and the ball was just jumping out of my hand.”

Catcher Henry Davis is one of the many Pirates players who appreciates what Falter has brought to the table.

“He’s been great,” Davis said. “He trusts his stuff, he throws the ball over the plate. I love catching him.”

Falter has still been somewhat obscured on a very good starting Pirates pitching staff that is headed by generational ace Paul Skenes and former All-Star Mitch Keller. But to his teammates, he’s been extremely visible and valuable.

“Bailey is steady,” relief pitcher Ryan Borucki said. “He’s making pitches — he’s doing a really good job for us. Every time that he goes out there, he gives us a chance to win.”

Falter — a native of Chino Hills, Calif. who grew up idolizing former Los Angeles Dodgers left-handed pitching legend Sandy Koufax — was taken by the Philadelphia Phillies in the fifth round of the 2015 MLB Amateur Draft.

His days with the Phillies were a mixed bag of challenges and fulfillment. Falter made his major league debut with the Phillies in 2021, but during his tenure in the Philadelphia organization, he spent time pin-balling between the major leagues and the Phillies Class AAA Lehigh Valley affiliate.

Falter worked as both a starter and a reliever with the Phillies, carding a 6-4 record with a 3.86 ERA in 20 appearances, including 16 starts, with Philadelphia in 2022, when he drew a starting assignment for the Phils in Game 4 of their National League Championship Series against the San Diego Padres. Falter lasted only 24 pitches in that outing, allowing four runs before being relieved in the first inning.

An injury sustained by another Philadelphia pitcher opened the door for Falter to begin the 2023 season as a member of the Phillies’ starting rotation. Falter struggled, however, going 0-7 with a 5.13 ERA in eight games before being optioned back to Lehigh Valley.

On Aug. 1 of that 2023 season, the Phillies traded Falter to the Pirates in exchange for infielder Rodolfo Castro. The trade has turned out to be a blessing for Falter, who has come into his own for the Pirates.

“When the Phillies traded me over here, Sam Fuld, (who at that time was) the Phillies’ general manager, said nothing but good things about (the Pirates),” said Falter, who is scheduled to make his next start today when the Pirates open a nine-game road trip against the Seattle Mariners. “It’s just been a better opportunity for me here. I feel like we have a lot of great arms in this organization.

“I’ve had a little bit more of a chance to blossom here, and I feel like I’ve taken advantage of that as much as I can.”