It appears the White Sox have lost starter Lucas Harrell to waivers. The Astros have apparently claimed the 26 year old righty who made three starts for the Sox in 2010 (in 8 total appearances), and saw action in three relief appearances this year. That the White Sox would expose Harrell to waivers isn't necessarily a huge deal with the team still running it's six man rotation, but he was probably the organizations best in-house option should the rotation suffer another injury (starter John Danks is currently on the disabled list).
Harrell was lost when the team decided to try and pass him through waivers, and replace him with Hector Santiago who has been strong in his first two MLB outings following solid outings in both High A, and AA this season. With few other available options, it would appear that Santiago will become the White Sox defacto emergency starter should the need arise.