So I guess that thumb isn't ready to hold a bat, as the Astros placed him on the DL retroactive to March 29. This means he'll be eligible to come off the DL on April 13. Brian Bixler has been recalled to take his place.
Ultimately, it's the right call. As much as you'd like to see Lowrie out there, it's better to let him rest it for another week than run the risk of further injury. Obviously.