The Astros designated Whitcomb for assignment Monday, Brian McTaggart of MLB.com reports.
The transaction frees a spot on the 40-man roster for the addition of waiver claim Nelson Velazquez. Whitcomb has slashed just .167/.216/.292 in his limited opportunities at the big-league level the past three seasons. The 27-year-old has hit .265/.342/.479 at the Triple-A level and can play all over the field defensively, so he could draw interest via waivers.