De Los Santos was optioned to Triple-A Lehigh Valley following Tuesday's win over the Mets.
De Los Santos earned the win Tuesday by allowing three runs on five hits over 6.1 innings -- he struck out six and walked three -- but will nonetheless return to the IronPigs with Vince Velasquez (forearm) poised to come off the disabled list Wednesday. De Los Santas performed well in his big-league debut, and may have earned himself another look when the Phillies are in need of a replacement starter during the second half of the season.