Triple-A Gwinnett activated Hernandez (elbow) from its 7-day injured list May 9 and assigned him to Double-A Mississippi.
Hernandez opened the season on the shelf while he finished up his recovery from February 2022 Tommy John surgery, but he was cleared to begin a rehab assignment with High-A Rome in mid-April. Though Hernandez allowed six runs (five earned) while striking out six and walking five over 5.1 innings across his six relief appearances with Rome, Atlanta saw enough from him to conclude he was ready to join the Mississippi bullpen. He turned in a scoreless inning in his first appearance for Mississippi last Wednesday.