Holcombe comes to York with three professional seasons under his belt. He spent the 2017 season in the United Shore Professional Baseball League with the Westside Woolly Mammoths, posting a 7-3 record with a 2.68 ERA. He totaled 78 strikeouts over 94.0 innings in 17 games and worked eight shutout innings with six strikeouts in a playoff game and got the win. In 2015 and 2016, Holcombe pitched for the Washington WildThings and Normal CornBelters of the Frontier League. The right-hander combined to make 16 appearances, including six starts, and throw 42.0 innings with Washington and Normal. Holcombe played his college ball at Faulkner University.