De Los Santos signed with the Mariners out of the Dominican Republic on July 17, 2014. Ward was the Mariners' 12th-round pick out of the University of Georgia in the 2014 Draft.
Benoit, 38, was 10-7 with a 1.96 ERA and 13 saves in 120 appearances over the past two seasons with the Padres. He signed as a free agent with the Padres on Dec. 28, 2013, and recently had his option picked up for the 2016 season.
De Los Santos made his United States debut last summer and was a combined 6-0 with a 3.47 ERA with 71 strikeouts over 62 1/3 innings in 13 starts at Arizona's two rookie-level affiliates. The native of San Pedro de Macoris, Dominican Republic, was 3-0 with a 2.55 ERA in five starts with the Mariners of the Arizona Rookie League.
He advanced to Class A short season Everett of the Northwest League where he was 3-0 with a 4.06 ERA in eight starts. De Los Santos allowed a combined 61 hits in his 62 1/3 innings, allowing 1.27 baserunners per inning while striking out 10.25 hitters per nine innings.
The left-handed hitting Ward hit a combined .278 with 19 doubles, 13 triples, nine home runs and 55 RBIs last season in 122 games at both levels of full season Class A in the Mariners' system. He spent the majority of the season at second base, although he also played third and shortstop.
He opened the 2015 with Class A Clinton of the Midwest League and hit .270 in 46 games. He actually hit better with Bakersfield after being promoted to the Class A Advanced California League, batting .282 in 76 games with 12 doubles, six triples and seven homers with 39 RBIs and 54 runs scored. He had a .362 on-base percentage and a .436 slugging percentage.
Benoit was 6-5 with a 2.34 ERA in 67 appearances for the Padres in 2015. The 6-foot-4 right-hander has a career record of 54-42 with 50 saves and a 3.84 ERA in 661 Major League appearances, including 55 starts. He was the eighth-inning setup man for closer Craig Kimbrel for the Padres in 2015.