Prospect of the Day: Kelvin Herrera, RHP, Kansas City Royals
The youth movement continues in Kansas City, with the arrival of right-handed reliever Kelvin Herrera.
Kelvin Herrera was signed by the Royals as a free agent from the Dominican Republic in 2006. He made his North American debut with Burlington in the Appalachian League in 2008, posting a 1.42 ERA with a sharp 45/5 K/BB in 51 innings. However, he missed almost all of the 2009 season with elbow problems, pitching just five innings in Low-A. Further elbow woes limited him to 41 innings in 2010, with a 4.35 ERA and a 40/15 K/BB in the Low-A Midwest League. He entered 2011 as a big question-mark.
Herrera was a starting pitcher at first, but converted to relief this year to help avoid the persistent elbow trouble. The results were excellent: 0.61 ERA with a 12/2 K/BB in 15 innings in High-A, 1.75 ERA with a 40/6 K/BB in 36 innings in Double-A, and a 2.12 ERA with an 18/7 K/BB in 17 innings in Triple-A. His composite line for the year: 1.60 ERA, 70/15 K/BB in 68 innings, just 42 hits allowed, a 2.07 GO/AO, and 14 saves.
Age 21, Herrera is small for a right-hander at 5-10, 190. There is nothing small about his arm strength however. He worked in the 90-94 range as a starter, but in relief this year he boosted his velocity into the mid-to-upper-90s. The fastball has unusually good movement low in the strike zone, resulting in a high ground ball rate. His slider was rated below average until this year, but now rates as above average. He already had a good changeup, so the development of his breaking ball and more consistent peak velocity readings made him truly dominating in the pen. He can throw strikes with all three pitches.
Herrera came a long way very quickly this year, and his walk rate spiked at Omaha. Some consolidation time in Triple-A might be in order to begin 2012. Nevertheless, he looks like a key component of the bullpen in the near future, and he might get a shot to close games at some point.