Eric O'Flaherty, a left-handed pitcher, began his Major League Baseball career with the Seattle Mariners. Drafted in the sixth round of the 2003 MLB Draft, he made his debut with the Mariners in 2006. O'Flaherty's early years in Seattle saw him working primarily out of the bullpen, where he demonstrated his ability to handle various relief situations. His time with the Mariners, however, was marked by ups and downs, as he sought to establish himself in the majors.

In 2009, O'Flaherty's career took a new turn when he was claimed off waivers by the Atlanta Braves. It was with the Braves that he found a more stable role and began to flourish as a reliable relief pitcher. Over the next several seasons, O'Flaherty became an integral part of the Braves' bullpen, particularly excelling in the role of a setup man. His performance in 2011 was especially noteworthy, as he posted a remarkable 0.98 ERA over 78 appearances, becoming one of the most dependable relievers in the league that year.

O'Flaherty's tenure with the Braves was characterized by his effectiveness against left-handed hitters and his ability to induce ground balls, thanks to his sinker-slider combination. His contributions were vital in helping the Braves maintain a strong bullpen, which was a key component of their competitive teams during that period. Unfortunately, his time in Atlanta was cut short by an elbow injury that required Tommy John surgery in 2013, sidelining him for the remainder of the season and part of the next.

After recovering from surgery, O'Flaherty signed with the Oakland Athletics in 2014. His stint with the Athletics was brief, as he was traded to the New York Mets in 2015. With the Mets, O'Flaherty continued to serve as a bullpen option, though he struggled to regain the form he had displayed earlier in his career.

In 2016, O'Flaherty returned to the Braves, hoping to recapture some of his previous success. However, injuries and inconsistency limited his effectiveness, and he was released by the team later that year. He made a final attempt to continue his career with the Cleveland Indians in 2017, but after being released during spring training, O'Flaherty's professional playing days came to an end.