Flores was added to the White Sox 40–man roster following the 2019 season.[8]
Flores made his MLB debut against the Kansas City Royals on September 3, 2020. With the 2020 Chicago White Sox, Flores appeared in 2 games, compiling a 0-0 record with 9.00 ERA and 2 strikeouts in 2.0 innings pitched.[9]
St. Louis Cardinals
On April 1, 2021, Flores was claimed off waivers by the St. Louis Cardinals.[10] Flores made one appearance with the Cardinals, spending most of his time with the Triple-A Memphis Redbirds, before he was designated for assignment on June 22, 2021.[11]
Colorado Rockies
On June 24, 2021, Flores was claimed off waivers by the Colorado Rockies and optioned to the Triple-A Albuquerque Isotopes.[12] He was designated for assignment on September 18.[13] Two days later, Flores was assigned outright to the Triple-A Albuquerque Isotopes. On April 1, 2022, Flores was released by the Rockies organization.[14]
Cincinnati Reds
On April 1, 2022, the same day he was released by the Rockies, Flores signed a minor league contract with the Cincinnati Reds organization and was assigned to the Triple-A Louisville Bats.[15] He was released on May 21, 2022.[15]
Diablos Rojos del México
On June 3, 2022, Flores signed with the Diablos Rojos del México of the Mexican League. He appeared in 7 games, making 6 starts with a 1-0 record and 4.15 ERA with 27 strikeouts in 26.0 innings pitched.[16]
Texas Rangers
On February 3, 2023, Flores signed a minor league contract with the Texas Rangers organization.[17] He was assigned to the Triple-A Round Rock Express to begin the year,[18] but struggled to an 0-1 record and 7.71 ERA with 4 strikeouts in 4.2 innings pitched across 3 games (1 start). He was released by the Rangers on April 25.[19]
Diablos Rojos del México (second stint)
On May 6, 2023, Flores signed with the Diablos Rojos del México of the Mexican League.[15] In 4 starts, he posted a 0–1 record with a 5.93 ERA and 7 strikeouts in 13.2 innings.
Guerreros de Oaxaca
On June 23, 2023, Flores was traded to the Guerreros de Oaxaca of the Mexican League.[15] In 7 starts for the club, he compiled a 1–4 record and 6.35 ERA with 24 strikeouts across 34 innings pitched.
Flores made 8 relief outings for the Guerreros in 2024, struggling to a 14.73 ERA with 5 strikeouts across 7+1⁄3 innings of work. He was released by Oaxaca on May 10, 2024.[20]
Tigres de Quintana Roo
On June 12, 2024, Flores signed with the Tigres de Quintana Roo of the Mexican League.[21] He made 7 appearances (4 starts) for the Tigres, struggling to an 0–2 record and 8.38 ERA with 12 strikeouts across 19+1⁄3 innings pitched. Flores was released by Quintana Roo on December 17.[22]