This is probably the most difficult pick of the entire Astros all-time team. The Astros have had some tremendous pitchers come through their clubhouse.
In fact, the first guy we all probably think of is Nolan Ryan. He pitched more years with the Astros than any other single club, and he had some good years with them...though his best were already behind him.
In 1987 Ryan had a spectacular year (though very odd record-wise); he had a 2.76 ERA with 270 K's but only eight wins to 16 losses!
The Astros have also seen great pitchers like Larry Dierker, Roy Oswalt, and Mike Scott come through their organization.
But the greatest Astro pitcher of all time has to be J.R. Richard.
JR took some time before hitting his groove, but from 1976-1980 you'd be hard pressed to find a better pitcher in the game. In 1978 he had a 3.11 ERA with 303 K's, and in 1979 he bettered that with a 2.79 ERA and 313 K's!
Richard had tremendous potential but was struck down in his prime by a stroke midway through the 1980 season.