Marquez begins his first season with the Ducks and sixth in professional baseball. The pitcher spent five seasons as a member of the Kansas City Royals organization (2018-19, 2021-23) before joining the Flock. In 104 career appearances (13 starts), he accrued a 27-6 record with a 3.26 ERA, nine saves and 318 strikeouts to just 68 walks over 251.1 innings of work. He has reached the Triple-A level in each of the past three seasons. In 2023, the Venezuela native went 2-0 with a 4.41 ERA and 41 strikeouts in 22 appearances across High-A, Double-A and Triple-A.

The 25-year-old posted a minuscule 0.61 ERA in nine games during his rookie season in the Dominican Summer League. He went on to go 5-2 with a 2.50 ERA in 14 games (six starts) in 2019 at the rookie level and Single-A combined. Across three levels in 2021, the righty went 7-1 with a 3.26 ERA, one save and 101 strikeouts in 77.1 innings across 25 games (seven starts). Marquez was originally signed by the Royals as a free agent in 2018.