Tarnok was optioned to Triple-A Gwinnett on Monday.
Tarnok was added to the 40-man roster and was in major-league camp as one of Atlanta's top prospects, but he'll now shift over to the minor-league side. The 23-year-old right-hander finished last season at Double-A Mississippi and posted a 2.60 ERA, 1.11 WHIP and 61:15 K:BB over 45 innings (nine starts), and his big-league debut could be on tap in 2022 if he has a strong showing at the Triple-A level.