Hummel was outrighted to Triple-A Sugar Land by the Astros on Monday after clearing waivers.
Hummel was designated for assignment by the Astros on Wednesday, Matt Kawahara of the Houston Chronicle reports.
The Astros claimed Hummel off waivers from the Giants on Thursday, Ari Alexander of KPRC 2 Houston reports.
The Giants designated Hummel for assignment Thursday.
Hummel was optioned to Triple-A Sacramento by the Giants on Monday, Susan Slusser of the San Francisco Chronicle reports.
The Giants acquired Hummel from the Mets on Tuesday in exchange for cash considerations, Anthony DiComo of MLB.com reports.
The Mets designated Hummel for assignment Friday, Anthony DiComo of MLB.com reports.
The Mets claimed Hummel off waivers from the Mariners on Friday, Jeff Passan of ESPN.com reports.
Seattle optioned Hummel to Triple-A Tacoma on Saturday, Ryan Divish of The Seattle Times reports.
Hummel is starting at designated hitter and batting eighth for the Mariners in Friday's game in Cleveland.