From BR Bullpen
- Bats Left, Throws Left
- Height 6' 0", Weight 150 lb.
- High School Liceo Ramon Matias Mella
- Debut June 29, 2012
 Biographical Information
Leyson Septimo was signed by Arizona Diamondbacks scout Junior Noboa in February 2003. He made his pro debut with the DSL Diamondbacks (Boca Chica?), hitting .214/.319/.302 with 57 strikeouts in 182 AB. In 2004, he improved to .276/.335/.371. Coming stateside with the 2005 Yakima Bears, Septimo batted .241/.272/.329 and led Northwest League outfielders with seven errors.
Septimo produced at a .251/.310/.346 rate for the 2006 South Bend Silver Hawks. Baseball America rated him as having the best outfield arm in the Midwest League. He improved his batting line to .271/.322/.373 for the 2007 Visalia Oaks and had 11 assists in 92 games in the outfield. Baseball America ranked him as having the top arm of any outfielder in the California League.
Septimo had hit .254/.305/.349 in 426 games in Organized Baseball. Given his outfield arm strength and insufficient bat for a flyhawk, Arizona converted him to pitching in the off-season. He would hit the high 90s with his fastball in his first couple years in that role.
In 2008, the southpaw hurler was 0-2 with a save and a 5.49 ERA for Visalia. He struck out 44 in 41 innings but walked 33 and threw 9 wild pitches before a shoulder injury ended his season in early August. Leyson split 2009 between Visalia (2-1, 6 Sv, 3.52, 44 K, 26 BB, 29 H in 38 1/3 IP) and the Mobile BayBears (0-1, 3 Sv, 7.85, 25 K, 18 BB, 6 WP in 18 1/3 IP). In the 2009 Futures Game, Septimo was the 5th of 9 World pitchers in a 7-5 win over the USA. Relieving Francisco Samuel with two on and one out in the 3rd, he allowed a run-scoring single to Pedro Alvarez but recovered to whiff both Chris Heisey and Tyler Flowers. Jhoulys Chacin relieved Septimo.
He pitched one game for the Aguilas Cibaenas in the Dominican League in 2009-2010. He opened 2010 back with Mobile and walked 14 in his first 10 2/3 innings, with an ERA over 7. He improved from there, going 2-2 with 4 saves and a 4.13 ERA for Mobile (23 BB, 37 K in 28 1/3 IP, only 16 H) and making it to AAA with the Reno Aces, where he was atrocious (0-1, 11.12, 30 BB in 17 IP). He was 2-1 with a 6.37 ERA and 25 walks to 22 strikeouts in 29 2/3 innings for Mobile after 23 games in 2011. He was then sold to the Chicago White Sox. Assigned to the Birmingham Barons, he went 2-1 with a 4.10 ERA in 22 games, fanning 38 in 26 1/3 innings (though he still walked 16).
In 2012, Septimo started off hot with the Charlotte Knights (2-1, Sv, 1.48, 39 K, 16 BB in 30 1/3 IP, only a .135 opponent average). He reached the major leagues with the Chicago White Sox on June 29, 2012. He was called up to replace Will Ohman. He went 1-2-3 in his MLB debut against some tough competition. Relieving Nate Jones with a 14-7 lead in the bottom of the 9th against the Yankees, he got Mark Teixeira on a grounder then fanned both Alex Rodriguez and Robinson Cano.
Primary Source: 2010 Diamondbacks Media Guide