Kelvin Herrera burst onto the major league scene in 2012. After a less than impressive September debut in 2011, Herrera established himself as a major part of the Kansas City Royals bullpen. Armed with an explosive fastball and an excellent change, Herrera quickly became one of the Royals primary set up men. His performance that season, a 4-3 record with a 2.35 ERA and 77 strikeouts in 84.1 innings, appeared to signal that the Royals had another young fireballer to pair with Greg Holland to close out games. Herrera appeared to be on the verge of becoming a truly dominant reliever.
Instead, it turned out that the 2013 season was a tale of two halves for Herrera. Perhaps due to the pressure of being the Royals primary eighth inning option at the start of the season, Herrera struggled at the start of the year. Through June 23rd, when he was demoted back to the minors, Herrera was 3-5 with a 5.20 ERA. His strikeout to walk rate, which had been an excellent 3.67 in 2012, had decreased to 2.2. He just was not the same pitcher.
After spending a month in the minor leagues, Kelvin Herrera found himself once again. Inserted right back into the eighth inning upon his return on June 19th, Herrera finished out the 2013 season by going 2-2 with a 2.64 ERA over the final two and a half months. His strikeout to walk rate skyrocketed to just under seven to one, as he struck out 41 batters while issuing only six walks.
Typically, an increase in control of that magnitude indicates that a hard throwing pitcher dialed back the speed slightly. Yet, in Herrrera’s case, it was the exact opposite. After averaging 98.2 MPH with his fastball prior to being demoted, Herrera actually averaged 98.75 MPH upon his return. The biggest difference is that Herrera began mixing up his pitches more, using his changeup more frequently. With the 12 MPH difference between his fastball and changeup, Herrera was able to keep opposing batters off balance, getting them to strike out or ground out weakly.
At age 24 heading into this upcoming season, Herrera has already experienced both success and failure at the major league level. His struggles at the start of the 2013 season, and subsequent success in the second half, may be all that Herrera needed to become that second dominating arm to close out games for the Royals.
The Royals bullpen was the strength of the ballclub last season. If Kelvin Herrera is able to replicate his second half performance throughout the entirety of 2014, that may help to make an already strong relief corps that much better in the upcoming year.