Mike Hampton being on this list is probably a surprise to some fans, but I think he at least deserves to be mentioned as a possible candidate. He was traded to the Astros in 1994 and became a starter for them in 1995. Hampton kept his ERA under 4.00 in each of his five seasons with the Astros and finished second in NL Cy Young voting in 1999 (Randy Johnson). That year, Hampton was 22-4 (good for best in the NL) with a 2.90 ERA and won his first of five Sliver Slugger Awards (which is the record for most by an MLB pitcher).
Hampton was traded from the Astros to the Mets in 2000, but returned to Houston on a one-year deal in 2008. He underwent full rotator cuff surgery in September 2009 and then retired from baseball in 2011 after attempting a comeback with the Diamondbacks. He spent four years in Atlanta, two in Colorado, and one each in Arizona, New York, and Seattle in 17-year career. Hampton was only with the Astros from 1994-99 and then again in 2009, but his impact as an All-Star pitcher deserves consideration. In seven seasons with Houston, Hampton was 76-50 with a 3.59 ERA and 1.37 WHIP in 172 starts. In the end, however, I don’t think he will get his jersey retired in Houston.