After placing pitcher Evan Meek on the 15-day DL with right shoulder tendinitis, the Pirates called Moskos up to the majors for the first time on April 30, 2011. On that same night, he made his Major League debut, pitching one scoreless inning in relief against the Colorado Rockies. On May 22, Moskos was optioned back to their Triple–A affiliate, the Indianapolis Indians. Less than a week later on May 28, Moskos was recalled to Pittsburgh due to Joe Beimel going on the 15-day DL with shoulder tightness. In 31 games in the majors, he was 1–1 with a 2.96 ERA.
Chicago White Sox
On July 6, 2012, Moskos was claimed off waivers by the Chicago White Sox.[5] He pitched for the Triple–A Charlotte Knights in 2012 and 2013. On June 23, 2013, he was released.
On November 18, 2013, Moskos signed a minor league contract with the Los Angeles Dodgers, including an invitation to major league camp. Later he was assigned to the Triple–A Albuquerque Isotopes, where he had a 6.52 ERA in nine games before being released on May 7, 2014.
In 2015, while he was a free agent, Moskos was suspended for 50 games following a positive test for a banned substance.[7] Moskos played in the Mexican Professional Winter League in Navojoa, Sonora for Mayos de Navojoa. In 24 games, he posted a 2–1 record with nine saves.
San Diego Padres
On March 1, 2016, Moskos signed a minor league contract with the San Diego Padres organization. He made 53 appearances out of the bullpen for the Triple–A El Paso Chihuahuas, compiling a 5–2 record and 3.39 ERA with 47 strikeouts over 61 innings pitched. Moskos elected free agency following the season on November 7.[8]
Lancaster Barnstormers
On December 20, 2016, Moskos signed a minor league contract with the Chicago Cubs.[9]
On April 26, 2018, Moskos signed with the Toros de Tijuana of the Mexican League. In 44 appearances for Tijuana, he compiled a 4–1 record and 1.24 ERA with 43 strikeouts and 7 saves across 43+2⁄3 innings pitched.