Callahan was called up by the Mets on Friday.
Callahan is set to make his major-league debut within the next few days as the 23-year-old earns his first promotion to the majors with roster expansion in full effect. During 10 innings with Triple-A Las Vegas since being traded to the Mets in late July, the right-hander has sported a 1.80 ERA and 1.60 WHIP over nine appearances. It seems unlikely that Callahan will get any high-leverage opportunities with the club, but he should get some quality time on the mound as the Mets look to see what they have in him.