Schugel is 2-2 with a 3.86 ERA over 49 innings in 34 relief appearances for the Pirates this season. He has allowed runs in just two of his 10 Triple-A outings since being optioned to Indianapolis on July 29.
The 24-year-old Frazier has hit .321 with a home run and seven RBIs in 84 plate appearances over 39 games with Pittsburgh.
Frazier has made starts at second base, right field, left field and third base for the Pirates.
Because Bristol's season ends Thursday, Frazier doesn't have to wait the usual 10 days before coming back to the Major Leagues. Instead, he can rejoin the Pirates on Friday.
Andrew Gruman is a contributor to MLB.com based in Milwaukee. This story was not subject to the approval of Major League Baseball or its clubs.