Darren O’Day is calling it a day.

O’Day, a key cog in the Orioles’ bullpen for seven seasons from 2012 to 2018, announced his retirement from baseball Monday after 15 years in the major leagues.

O’Day, 40, pitched for six different organizations and is best known for his submarine delivery — a style that made him one of baseball’s best set-up men during his prime. The Jacksonville, Florida, native ends his career with a 2.59 ERA and 21 saves in 609 innings.

“The mental, physical, and time demands have finally outweighed my love for the game,” O’Day wrote in a statement posted on Twitter. “When I started in 2006, I didn’t know if I was good enough to compete in MLB, but I was determined to keep going until someone told me otherwise. I hope anyone out there who does things a little different can find inspiration in my story.”

O’Day was signed as an undrafted free agent out of college and made his major league debut in 2008 with the Los Angeles Angels. After a brief stint with the Mets in 2009, he was claimed by the Texas Rangers and had back-to-back successful seasons. But after struggling in 2011, he was waived by Texas and claimed by Baltimore.

While in Baltimore, O’Day was arguably one of the most effective relievers in the majors with a 2.40 ERA, a 0.994 walks and hits per innings pitched, 19 saves and a 28-14 record in 374 1/3 innings. After good seasons in 2012 and 2013, O’Day was dominant in 2014 and 2015 — posting sub-2.00 ERAs and sub-1.00 WHIPs. His lone All-Star nod came in 2015 amid the best season of his career, in which he threw 65 1/3 innings with a 1.52 ERA and saved a career-high six games.

The Orioles traded O’Day and starting pitcher Kevin Gausman to the Atlanta Braves in a deal that initiated Baltimore’s rebuild. O’Day pitched in each of the next four seasons — three with Atlanta and one with the New York Yankees — but only totaled 54 innings. He had a 4.15 ERA and 26 strikeouts in 21 2/3 innings with the Braves in 2022.

“As a lightly recruited high school player, to a college walk-on, to an undrafted free agent, to a non prospect entering pro ball, I am extremely proud of playing with the best players in the world for so long,” O’Day wrote. “Finally, after 17 seasons in professional baseball, it is time to go home.”

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