Eflin will start Tuesday's game against the Blue Jays for his major league debut, Todd Zolecki of MLB.com reports.
Eflin will make his start in the place of Vince Velasquez, who was placed on the 15-day disabled list Friday with a right biceps strain. Throughout the 2016 season with Triple-A Lehigh Valley, Eflin has compiled a 5-2 record with a 2.90 ERA in 68.1 innings of work. The 22-year-old pitched 5.1 scoreless innings Thursday and has a chance to make an impression against the Blue Jays in Toronto.