Roger Clemens joined the Houston organization in early 2004 as a high-profile free agent, a move that stunned the baseball world and brought the most decorated pitcher of his generation back to his adopted hometown. After a brief "retirement" following his tenure in New York, he signed a one-year deal to pitch alongside his close friend Andy Pettitte, instantly transforming the Astros from a contender into a World Series threat. For three seasons in a Houston uniform, he served as the veteran-like presence at the top of the rotation, proving that even in his forties, he could dictate the terms of a game through a high-velocity repertoire and a legendary competitive drive.

After arriving in Spring Training with the eyes of the city upon him, he demonstrated a specialized ability to defy the typical aging curve of a power pitcher. He surged out of the gate with a 9-0 start, showing the organization that he was still a foundational ace.  during that 2004 campaign. That summer, he evolved into the premier starter in the National League, recording an 18-4 record and a 2.98 ERA. He showed the organization that he was a foundational winner, winning his record-breaking seventh Cy Young Award and becoming one of the few pitchers to secure the hardware in both leagues. He possessed a rare, durable quality that saw him strike out 218 batters over 214 innings and lead Houston to within one game of the World Series.

He followed this up in 2005 with perhaps his most impressive statistical outlier, leading the major leagues with a microscopic 1.87 ERA and a league-best 2.87 FIP, finishing third in the Cy Young voting at age 42.  Following the 2006 season, he eventually returned to New York to finish his career.

With the Astros, Rocket compiled a 38-18 record, a 2.40 ERA, and 505 strikeouts in 539 innings of work.