I'll add some names to the Mt. Rushmore of underappreciated Astros... and I'm basing that term on unretired numbers.
Dave Smith- 11 years with the Astros producing 216 saves and a 130 ERA+
Joe Sambito- 8 years with the Astros producing a 140 ERA+ and throwing 40 consecutive scoreless innings in '79
Cesar Cedeno- 12 years with the Astros producing 5 gold gloves, 1600 hits, 480 steals, and a 129 OPS+
Billy Doran- favorite Astro during my college years. He was a beautiful baseball player. Don't judge.
Also, regarding a retired number player, keep in mind that Jeff Bagwell played 9 years in the Astrodome, where he hit 269 of his 449 career home runs. He might have hit 550 in his career if he played all home games at MMP.
I love Texas Aggie sports, but I love Texas A&M more.