Kelvin Herrera is a former starting pitching prospect that could not stay healthy. But, he has an electric arm that is well suited for the bullpen. He throws an excellent 95-96 mph fastball and has a plus change up around 80 MPH. He has a very good curveball but it is still very inconsistent.
The Royals signed Herrera out of the Dominican Republic as a 17 year old and now at the age of 21 he has a terrific overall playing card. He has a career mark of 13-7 with a e.r.a of 1.99. He has struck out 152 and walked just 39 in 163 innings.
He is part of arguably the best lefty-righty combo in the low minors as he and 2010 draft pick Kevin Chapman are as good as they come for the Wilmington Blue Rocks