Jon Matlack's baseball career is marked by his achievements as a left-handed pitcher in Major League Baseball (MLB), primarily known for his tenure with the New York Mets and later with the Texas Rangers. Matlack's professional journey in the MLB began when he was drafted in the first round, fourth overall, by the New York Mets in the 1967 Major League Baseball Draft. Making his MLB debut on July 11, 1971, Matlack quickly established himself as a formidable pitcher.

In 1972, Matlack's first full season in the majors, he earned the National League (NL) Rookie of the Year award, a testament to his immediate impact on the field. His performance that year was highlighted by a remarkable 2.32 ERA over 32 starts, showcasing his ability to dominate opposing hitters. Throughout his tenure with the Mets, Matlack was known for his precision and effectiveness on the mound, contributing significantly to the team's pitching rotation.

One of Matlack's most memorable moments came in the 1973 season when he played a crucial role in leading the Mets to the National League pennant. Although the Mets ultimately fell to the Oakland Athletics in the World Series, Matlack's performances, including a complete-game victory in Game 2 of the series, were pivotal. His excellence was not limited to the regular season; he also shone in the postseason, demonstrating his capability to perform under pressure.

Matlack's tenure with the Mets also included three All-Star selections (1974, 1975, and 1976), highlighting his status as one of the top pitchers in the league during the mid-1970s. Despite his success, his time with the Mets came to an end after the 1977 season, when he was traded to the Texas Rangers as part of a four-team deal.

With the Texas Rangers, Matlack continued to be a reliable starting pitcher. He recorded 15 wins in his first season with the team in 1978 and maintained a strong presence on the mound throughout his time in Texas. His performance helped solidify the Rangers' pitching staff, and he remained with the team until his retirement from professional baseball following the 1983 season.

Over the course of his 13-year MLB career, Matlack compiled a record of 125 wins and 126 losses, with an earned run average (ERA) of 3.18. He struck out 1,516 batters over 2,363 innings pitched, demonstrating his ability to consistently challenge and overpower hitters. Despite his individual success, Matlack's teams never captured a World Series title during his career, though his contributions to the game were significant and enduring.

In summary, Jon Matlack's baseball career is characterized by his effectiveness as a starting pitcher, his contributions to the New York Mets' pennant-winning 1973 season, and his consistent performance both with the Mets and the Texas Rangers. His accolades, including the NL Rookie of the Year award and multiple All-Star selections, reflect his standing as one of the notable pitchers of his era.