He made his professional debut in 2018, splitting the year between the Single–A Rome Braves and High–A Florida Fire Frogs, for whom he accumulated a 4.50 earned run average (ERA) with 36 strikeouts across 21 games.
[4] Hernández began the 2023 season with High–A Rome, where he made six appearances, logging a 2–0 record and 8.64 ERA before being promoted to Double–A Mississippi.
[6] On July 23, 2023, the Braves promoted Hernández to the major leagues for the first time, and he made his debut later that day against the Milwaukee Brewers.
[13] He ended the regular season having pitched 3+2⁄3 innings across four appearances for the Braves, recording three earned runs on six hits and three walks.
Hernández was activated from the injured list and added to the Braves' roster for the 2023 National League Division Series against the Philadelphia Phillies.