A native of the Dominican Republic, De Los Santos signed with Seattle at the age of 18. He would make his professional debut in 2015 in the Rookie level Arizona League. There, he posted a 3-0 record with a 2.55 ERA in five starts. The righty earned a promotion to Class A short-season Everett where he would notch a 3-0 record with a 4.06 ERA through eight starts.
During the following off-season, he was traded to the Padres in a deal for Joaquin Benoit.
In 2016, making his debut in the Padres organization, De Los Santos would open the season with Class A Ft. Wayne. In 11 appearances (seven starts), he tallied a 3-2 record with a 2.91 ERA and a .199 batting average against.
De Los Santos was promoted to Class A Advanced Lake Elsinore in June. As a member of the Storm rotation he would sport a 5-3 record with a 4.35 ERA and a 6.8 K/9 mark in 15 starts.
In 2017, he moved up to Double-A San Antonio. There, he posted a 10-6 record with a 3.78 ERA, an 8.3 K/9 mark as well as a .237 BAA. De Los Santos improved greatly as the season went on, seeing his 4.92 ERA in the first half improve after tallying a 2.75 ERA following the All-Star break.
Listed at six-foot-three and 170-pounds, the 22-year-old features a fastball that regularly clocks around 94-95 MPH and features sink to help draw ground ball outs. Additionally, he offers a curve ball, a solid change up along with a nice slider that can present concern if he hangs it for the opposition. The slider was a new addition to his repertoire, so he's still working to refine it.
After quickly moving through the SD system, De Los Santos should land at the Triple-A level this year for the Phillies.
Some may view De Los Santos as being far from a finished product, but he has all the tools to become a stable part of a big league starting rotation in the comings seasons.
You can keep track of this year's Phillies prospect countdown at this link.