Serrano agreed to a $300,000 deal with the Cubs on Sunday.
At 17, Serrano is one of the older prospects in this year's July 2 signing class. His fastball has topped out at 94 mph, but he typically sits at around 90 mph. Serrano's curveball is his best secondary pitch -- a potential plus offering. He also throws a changeup. At 6-foot-1, 180 pounds, he has good size for his age, but there is some effort in his delivery, which adds some bullpen risk to the profile.