The title essentially speaks for itself. The Royals bullpen features many very good pitchers, one of which is Kelvin Herrera. Dave Cameron highlighted a recent performance from the Royals bullpen over at FanGraphs, a game in which Herrera faced four batters and struck out all four. Cameron also took to Twitter that day stating that Herrera may be the most underrated reliever in baseball. He may be right, as Herrera has been outstanding this season.
I’m not new to the Herrera bandwagon, he appeared as the third ranked prospect for 2012 in the Royals 5×5 series here in March, and I highlighted him in April as part of the AL Waiver Wire series at The Hardball Times. Suffice to say, I’m not only not new to the bandwagon, I may be driving it. Herrera does everything you’d hope a high leverage reliever would do. He strikes batters out at a high rate, 8.47 K/9, limits free passes, 1.60 BB/9, and he induces groundballs in bunches, 57.3 percent GB rate. That formula has has resulted in a solid 2.97 ERA that is supported by his 3.03 FIP, 2.81 xFIP, 3.01 tERA, and 2.27 SIERA. His WHIP is a very fantasy friendly 1.01, and his pitching has made him a sneaky good ratios option in leagues where non-closing relievers have value.
A look at his Brooks Baseball player card yields further evidence that Herrera has the goods to work in high leverage late innings opportunities. He isn’t a guy getting by with deception, he posseses an electric arsenal. Herrera throws three pitches, a fastball, curveball and a change-up. His fastball is a premium heater, averaging 98.89 mph. As one would expect, that type of cheddar has helped him post an above average whiff/swing rate on the pitch. His slowest offspeed offering is his curveball, which sits in the low-80s with an average velocity of 81.54 mph. It’s the pitch he throws least often, with a seven percent usage rate. In addition to being the least used pitch in his arsenal, it has also has been his worst bat missing pitch. Still, it is a nice weapon for Herrera to have at his disposal when looking to change speeds and attack opposing hitters. His best pitch has been his change-up. The numbers supporting that claim are what is important, but to my untrained eyes, it is a true gem as well. The pitch is incredibly deceptive because his arm action is the same on his fastball as it is on his change-up. Of course, the velocity disparity between the two pitches, just over 10 mph, has left some hitters looking foolish getting out in front and flailing helplessly. Herrera has a 25.12 percent whiff rate on his change-up, and his 125 PitchIQ score for his whiff/swing rate makes it a well above average bat misser. He has been hell on right-handed hitters, .255 wOBA, but his repertoire has allowed him to torment left-handed batters as well, .298 wOBA. To put things in perspective, the league average wOBA this year is .315. To further hammer his dominance home, just four qualifying batters have a wOBA below .255, and just 33 qualifying batters have a wOBA below .298.
The Royals have used Herrera in a variety of situations. He has pitched more than one inning in 15 of 34 appearances this year. He has come into games the team has been leading, and games the team has been trailing in. He isn’t likely to be the first name called upon to take over closer duties if Jonathan Broxton is dealt, but it is at least possible he vultures a few saves down the stretch if a trade does in fact happen. In the mean time, even without saves, his contributions make him one of the most desirable middle relievers to own in large mixed leagues and AL-only formats.