De Los Santos walked the first batter he faced to load the bases -- which he attributed to serious nerves -- but settled down, getting a groundout and a strikeout to set down the Mets.
"I got my job done," he said in front of his locker, which contained the game's lineup card and a ball from his outing.
The 22-year-old had a 2.65 ERA in 26 outings with Double-A Harrisburg this season.
Jacob Emert is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.