Acquired last winter from the Red Sox along with Rubby De La Rosa in a deal that sent Wade Miley to Boston, Webster spent most of the 2016 season with Triple-A Reno where he was 4-6 with an 8.18 ERA.
In nine games, five starts, with the D-backs Webster was 1-1 with a 5.81 ERA.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.