Feltner attended Walsh Jesuit High School in Cuyahoga Falls, Ohio.

[6] Feltner made his professional debut with the Grand Junction Rockies and pitched 2019 with the Asheville Tourists.

[7] He did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.

[9] That day, he made his MLB debut, taking the loss after allowing 6 earned runs, including a game-winning solo home run by Ozzie Albies off Feltner's first major league pitch, in 2.2 innings of work in a 9–2 loss to the Atlanta Braves.

[10] On May 13, 2023, in a start against the Philadelphia Phillies, Feltner was hit in the head by a 92.7-mph line drive off the bat of Nick Castellanos.