The thinking is probably to let him get his first appearance as a starter as thats what he's most used to, plus its even in a minor league ballpark. He will pitch a few innings and than Lauer pitches a few. Buys Berrios and Bassitt another day of rest, who have clearly benefited from it. Bieber and Gausman will probably still start on 4 days rest, so you're basically just replacing a Berrios start with a Yesavage/Lauer start.