One of the top pitchers in franchise history, the Mississippi native has twice won 20 games but never won a Cy Young Award. In ten seasons, he came one victory shy of the franchise record, posting a 143-82 record with an ERA of 3.24.

Oswalt has also been a "money" pitcher, posting a 4-0 record with a 3.66 ERA in post-season competition while with Houston and clinching the Astros' first World Series appearance with a masterful win in St. Louis in Game 6 of the 2005 NLCS. His effort earned him a bonus from owner Drayton McLane - a tractor for his Mississippi farm.

The three-time All-Star was traded to Philadelphia on July 29, 2010, rather than wait through a rebuilding effort. It turned out to be a wise decision as the Astros would not have a winning season again until 2015.

On April 5, 2014, Oswalt and fellow Astros legend Lance Berkman signed one-day personal services contracts so they could officially retire together as Astros.