Koumas had some outstanding achievements in high school ultimately leading him to be a draft pick by the Texas Rangers in the 48th round of the 2010 MLB draft. He was also the 2010 HS Louisville Slugger All-American.

Following high school, he played three seasons with the South Carolina Gamecocks and was a three year letterwinner. In 2011, Koumas was named to the SEC All-Freshman Team. He went 6-1 with a 2.96 ERA in the 19 games he appeared in (12 of the starts). He also had 63 strikeouts over the 73 innings he pitched. He pitched in the College World Series game vs. Florida with an impressive outing of just one run on three hits in 5.2 innings. In his sophomore season in 2012, he appeared in 18 games and had a 4.82 ERA. His senior season with the Gamecoks he struggled for a majority of the season but was one of three Gamecoks to combine for a no hitter against Albany. 

Currently in the USPBL, Koumas a 4-0 record with a 2.57 ERA in the 11 games he appeared in. He started in 5. He also has 34 strikeouts in the 35 innings he has pitched.