Gary Waslewski, a right-handed pitcher, embarked on his Major League Baseball career with the Boston Red Sox. Born on July 21, 1941, in Meriden, Connecticut, Waslewski attended the University of Connecticut before signing with the Pittsburgh Pirates as an amateur free agent in 1960. However, it was with the Red Sox that he would make his MLB debut.

In 1967, Waslewski was called up to the majors and made his debut on June 11. That year, the Red Sox were in the midst of a remarkable season, often referred to as the "Impossible Dream" season, where they clinched the American League pennant. Waslewski played a role in this journey, appearing in 12 games and starting in 10 of them. He posted a 2-2 record with a 3.21 ERA, which helped solidify the Red Sox's pitching staff during a crucial stretch of the season.

The highlight of Waslewski's rookie year came during the 1967 World Series against the St. Louis Cardinals. In Game 6, with the Red Sox facing elimination, he was given the start. Waslewski pitched well, allowing just two runs over five innings, helping the Red Sox to a 8-4 victory and forcing a decisive Game 7. Although the Red Sox ultimately lost the series, Waslewski's performance was a bright spot in their postseason run.

Following the 1967 season, Waslewski continued his career with the Red Sox in 1968, appearing in 31 games and starting 16. He finished the season with a 4-7 record and a 3.69 ERA. Despite his efforts, the Red Sox were unable to replicate their previous year's success.

In December 1968, Waslewski was traded to the St. Louis Cardinals in exchange for infielder Dick Schofield. His time with the Cardinals was brief, as he appeared in only 12 games during the 1969 season, posting a 1-1 record with a 4.28 ERA.

Later in 1969, Waslewski was traded to the Montreal Expos, an expansion team in their inaugural season. With the Expos, he found more opportunities to pitch, appearing in 22 games and starting 15. He recorded a 5-7 record with a 4.10 ERA, providing stability to a young pitching staff.

Waslewski's journey in the majors continued as he was traded once more, this time to the New York Yankees in 1970. During his tenure with the Yankees, he appeared in 36 games, primarily as a reliever, and posted a 2-2 record with a 3.34 ERA. His ability to adapt to different roles on the pitching staff was evident during his time in New York.

In 1971, Waslewski was purchased by the Oakland Athletics, but he did not appear in any games for them. Instead, he spent the season in the minor leagues, playing for the Iowa Oaks, the Athletics' Triple-A affiliate. This marked the end of his major league career, as he did not return to the big leagues after the 1971 season.

Throughout his MLB career, Gary Waslewski played for four different teams, appearing in a total of 117 games and starting 47 of them. He finished with a career record of 11-26 and an ERA of 3.44. While his time in the majors was relatively brief, he experienced the highs of a World Series and the challenges of playing for an expansion team.