From BR Bullpen
- Bats Right, Throws Right
- Height 6' 3", Weight 210 lb.
- High School Belen Jesuit High School
 Biographical information
Gaby Hernandez began his professional career in 2004.
Hernandez began his professional career in 2004, splitting the season between the GCL Mets and Brooklyn Cyclones. In 10 games with the GCL Mets, he went 3-3 with a 1.09 ERA and 58 strikeouts in 49 2/3 innings. He allowed only 25 hits for a .150 opponent average. He appeared in only one game for the Cyclones, going 1-0 with six strikeouts in three innings of work. He tied Jair Jurrjens for the Gulf Coast League lead in complete games (2), was 5th in strikeouts (5 behind leader Gabriel Sosa) and easily led in ERA, .66 ahead of runner-up Scott Mitchinson. Despite his success, Mitchinson beat him out for the All-Star SP honors. Baseball America ranked him as the #2 prospect in the circuit, between Luis Soto and Greg Golson.
In 2005, he played for the Hagerstown Suns and St. Lucie Mets, going 6-1 with a 2.43 ERA and 99 strikeouts in 92 2/3 innings with the Suns (18 games started). On June 19, he threw a no-hitter against the West Virginia Power. He slumped with St. Lucie, however, going only 2-5 with a 5.74 ERA in 10 games started. Overall, he went 8-6 with a 3.47 ERA in 28 games started. In 135 innings, he struck out 131 batters and allowed 107 hits. Baseball America named him the #18 prospect in the South Atlantic League right ahead of Ian Desmond. On December 5, 2005, he was traded with fellow minor leaguer Dante Brinkley to the Florida Marlins for catcher Paul Lo Duca.
He spent the 2006 season with the Jupiter Hammerheads, going 9-6 with a 3.68 ERA in 20 games (19 starts) before missing the final month with a sprained right toe. He was 8th in the Florida State League in ERA. Baseball America rated him as the #13 prospect in the league, just ahead of fellow hurlers Johnny Cueto, Jaime Garcia and Jair Jurrjens. Hernandez spent the winter in the Puerto Rican League, going 3-2 with a 4.14 ERA.
With the Carolina Mudcats in 2007, he went 9-11 with a 4.22 ERA in 28 games started. He made the mid-season Southern League All-Star Game. Baseball America tabbed him as the 19th-best prospect in the league, just ahead of Alcides Escobar.
In 2005 and 2006, he was ranked the third-best prospect in the Mets organization by Baseball America. He was ranked the third-best prospect in the Marlins organization in 2007 and the fifth-best prospect in their organization in 2008.
He began the 2008 season in the Marlins organization, going 2-8 with a 7.24 ERA in 13 games started with the Albuquerque Isotopes and missed a month with an injury. He also started four games with the Mudcats; he went 3-0 with a 4.30 ERA. On July 31, 2008 - the trading deadline - he was traded to the Seattle Mariners for pitcher Arthur Rhodes. He went 1-1 with a 5.01 ERA in six games started with the West Tenn Diamond Jaxx, the team he played with following his trade. Overall, he went 6-9 with a 6.13 ERA. He went 2-5 with a 7.67 ERA for the Peoria Javelinas in the Arizona Fall League.
He pitched for the Tacoma Rainiers in 2009 and went 10-9 with a 5.23 ERA in 26 starts. In February 2010, he was claimed off waivers by the Boston Red Sox and less than a month later, the Kansas City Royals claimed him. He pitched for Kansas City's Triple-A squad, the Omaha Royals, that year and went 10-6 with a 4.91 ERA in 31 games (22 starts). In March 2011, the Royals traded Hernandez to the Chicago White Sox for cash. After beginning the year with their Triple-A team, the Charlotte Knights, he was acquired by the Arizona Diamondbacks partway through the season and pitched for the Triple-A Reno Aces. Combined, he was 8-13 with a 6.64 ERA in 26 starts that year.
Hernandez began 2012 in the independent leagues, pitching for the Southern Maryland Blue Crabs (5-1, 2.77 ERA) and Joliet Slammers (0-1, 0.00 ERA), before he was signed by Arizona and assigned to their Double-A club, the Mobile Bay Bears - with whom he was 0-8 with a 6.26 ERA in 14 games (10 starts). Overall, he was 5-10 with a 4.69 ERA. He spent all of 2013 with Southern Maryland and went 7-12 with a 4.29 ERA in 28 games (24 starts). He returned to Southern Maryland for 2014 and went 8-9 with a 4.50 ERA in 27 games (25 starts) and in 2015, he had a 2.84 ERA in three starts with the club.
Sources include the 2005-2008 Baseball Almanacs and 2009 Mariners Media Guide