He has previously played in Major League Baseball (MLB) for the Seattle Mariners, Pittsburgh Pirates, and Oakland Athletics.

[3] During his time with them, he played for the Gulf Coast Rays, Hudson Valley Renegades, Bowling Green Hot Rods, Charlotte Stone Crabs, Montgomery Biscuits, and the Durham Bulls.

[3] Markel split the 2016 campaign between Double–A Montgomery and Triple–A Durham, compiling a 7–3 record and 2.78 ERA with 58 strikeouts over 43 combined appearances.

[5] Markel signed a minor league contract with the Arizona Diamondbacks on December 18, 2017, but was released prior to the start of the season on March 25, 2018.

Markel spent the year with the Triple-A El Paso Chihuahuas, posting a 4.42 ERA with 91 strikeouts across 41 appearances.

Markel was designated for assignment on June 7, 2022, in order to make room for Matt Davidson on the team's 40-man roster.

[17] On June 8, 2022, Markel was claimed off waivers by the Chicago White Sox and optioned to the Triple-A Charlotte Knights.

On February 22, 2024, it was announced that Markel would be signing with the Hagerstown Flying Boxcars for their inaugural season of play in the Atlantic League of Professional Baseball.