The Cincinnati Reds added Contreras to their 40-man roster after the 2012 season.[1] He was named to appear in the 2013 All Star Futures Game.[2]
Contreras was called up to the Reds from the Double-A Pensacola Blue Wahoos on June 21, 2014,[3] and made his debut the same day against the Toronto Blue Jays in the ninth inning. In nine pitches he retired the side and recorded his first major league strikeout.[4] Contreras was released by the Reds on March 15, 2016.[5]
On April 20, 2017, Contreras signed with the Laredo Lemurs of the American Association of Independent Professional Baseball. When the Lemurs folded before the season started he signed on with the Texas AirHogs.[6]
On June 28, 2017, Contreras left the AirHogs to sign with the Vaqueros Unión Laguna of the Mexican Baseball League.[7] He was released on February 1, 2018.
On June 17, 2018, Contreras signed with the AirHogs. He was released on May 15, 2019. Contreras later re-signed with the AirHogs on August 1, 2019. In 2020, the team was not selected by the league to compete in the condensed season due to the COVID-19 pandemic. Contreras was not chosen by another team in the dispersal draft, and therefore became a free agent.
On February 18, 2022, Contreras was signed by Parma Baseball.[8] He made 16 appearances for the team, recording a 1.09 ERA with 60 strikeouts and 3 saves across 33.0 innings pitched.
On April 6, 2023, Contreras re–signed with Parma.[9] He pitched in 8 games for the club, logging a 1.20 ERA with 18 strikeouts across 15.0 innings of work.
On April 9, 2024, Contreras signed with the Saraperos de Saltillo of the Mexican League.[10] He made only one appearance for Saltillo, logging a scoreless inning with one strikeout.
On April 26, 2024, Contreras was traded to the Rieleros de Aguascalientes of the Mexican League.[11] In six appearances, he posted an inflated 15.43 ERA, giving up 8 earned runs in 4+2⁄3 innings. Contreras was released by the Rieleros on May 27.[12]
In 2025, Contreras signed with the Senadores de Caracas of the Venezuelan Major League.
