Darren O'Day, the submarining right-handed reliever who spent 15 seasons in the Majors, announced his retirement Monday.

“The mental, physical, and time demands have finally outweighed my love for the game,” the 40-year-old O’Day wrote in a social media post. "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 somebody told me otherwise.”

Undrafted out of the University of Florida, O’Day rarely threw above 90 mph, but he was able to sustain a long career in the big leagues thanks in large part to the deception created by his unique delivery. O’Day pitched for six clubs, was an All-Star Game selection for the Orioles in 2015 and held the fourth-best career ERA among active relievers with at least 600 innings pitched at the end of the 2022 season. His 2.59 mark was bested by only Craig Kimbrel, Kenley Jansen and Aroldis Chapman.

“I hope anyone out there who does things a little differently can find inspiration in my story,” O’Day wrote.

O’Day signed with the Angels in 2006 and made his MLB debut with them two years later. He struggled as a rookie, as he posted a 4.57 ERA through 43 1/3 innings, but one connection he made that season would go on to have a profound effect on his life.

O’Day was a member of the Mets in 2009 when he found out that his former teammate, Angels pitcher Nick Adenhart, had been killed in a car crash just as his promising career was starting to blossom. The tragic event changed how O’Day viewed his own career.

“Knowing every day wasn’t guaranteed, so I better make the most of each game, made me pitch with a freedom and a confidence that I was missing as a rookie,” wrote O’Day, who spent his 14 remaining seasons with Adenhart’s No. 34 written under the bill of his cap. “When I would get in to jams on the mound, I would take my hat off, see his number, and be reminded that bases loaded, no outs, was a small problem in the grand scheme of life. To Nick and his family I am forever grateful.”

O’Day’s stint in New York lasted only four appearances before he was waived and eventually picked up by the Rangers. He was extremely effective across 136 appearances for Texas from 2009-10, registering a 1.99 ERA. However, following an injury-marred 2011, O’Day found himself back on waivers.

He latched on with the Orioles prior to the 2012 campaign and began the most successful stretch of his career. O’Day was a part of three playoff teams in Baltimore and pitched to a 2.40 ERA over seven seasons with the O’s. His 21.5% strikeout-minus-walk rate from 2012-18 ranked 10th best among relievers who threw at least 300 innings.

He made at least 68 appearances in each of his first four seasons in Baltimore, but by the back half of his tenure, the injuries began to take their toll. Although he was often a valuable contributor when healthy, O’Day pitched in just 20 games in 2018 and never made more than 30 appearances in any of his final four seasons, which were split between the Braves and Yankees. His 644 games were the 12th most among active pitchers at the end of last season. All of them came in relief.

“As I got older and more reflective, I realized my favorite part about my time in the Major Leagues was being a teammate,” he wrote. “Being part of a group of determined individuals working to win a championship is the ultimate blessing of my career.

“I love you all and thank you for everything that we have shared."