Gaddis will be promoted from Triple-A Columbus to start Friday's game against the Astros, Ryan Lewis of the Akron Beacon Journal reports.
Gaddis has posted a 4.07 ERA with a 114:31 K:BB across 86.1 total innings between Double-A Akron and Columbus this season. He doesn't have much prospect pedigree but has consistently missed bats at every level of the minors. Gaddis will draw a tough matchup in his big-league debut, but he could have the chance to stick in the rotation until Aaron Civale (wrist) is ready to return.