A young Royals project who has not been afraid to make the necessary changes
While I was putting together my piece about the best individual pitches on the Royals, I was astonished to see the changes Angel Zerpa has made to his pitch arsenal. These adjustments have proven effective, and despite some early struggles, he is now having the best season of his career. Zerpas’s approach on the mound caught my attention, and I began to take a deeper look into his development over the years in Kansas City.
From the beginning, Zerpa was an intriguing prospect. In 2016, the Royals signed him out of Venezuela for $100,000, and they took their time moving him through the minor leagues. Zerpa was added to the 40-man roster in 2020 to protect him from Rule 5 before he ever played in A ball.
Zerpa started 2021 in A+ Quad Cities, where he played well but struggled as the Royals pushed him up through the organization. Zerpa even made a major league start in the 2021 season, where he went five scoreless innings, only allowing three hits. Zerpa was promoted straight from AA, where he had a 5.96 ERA over 45.1 innings, but his promising pitch metrics gave the Royals confidence he could hold his own in Kansas City.
The next year, Zerpa returned to AA, where he posted a 4.36 ERA over 64 innings and 13 starts. Zerpa returned to the majors in 2022, where he played in three games (two starts) and posted a 1.64 ERA over 11 innings. In the 2023 offseason, Angel Zerpa began to make a move to the bullpen. He struggled some, but began to find success later in the year and has stuck in his relief role for the last several years.
Through his journey in the Royals organization, Zerpa made a lot of tweaks and adjustments to his pitch mix. When he first came to Kansas City, Zerpa primarily used a four-seam fastball and slider mix, which accounted for more than 75% of his pitches. Zerpa’s four-seamer sat around 94 MPH and was a pitch he threw 50% of the time, but it got hammered in 2022, and a new pitching staff wanted to make some changes.
After the 2022 season, the Royals fired Cal Eldred and hired their new pitching coach, Brian Sweeney. In the offseason prior to the 2023 season, Sweeney worked with Zerpa, building his two-seam sinker and changeup while also reshaping his slider, adding 3 MPH to it and getting tighter spin. The new staff had Zerpa increase the usage of his sinker by 14% and reduce the usage of his four-seam.
In 2023, Zerpa started in Omaha due to an injury, refining his new sinker/slider mix, and had an okay year in Omaha, posting a 4.73 ERA in 26.2 innings. He was recalled on the first of August as a starter, but struggled to get deep into games. He had good numbers early in his starts, and because of that early success, the team elected to make him a full-time reliever. With Zerpa fully healthy and completing his move to the bullpen, the Royals made some tweaks and worked with him on pitch selection again.
In 2024, Brian Sweeney yet again pushed for Zerpa to increase the usage of his sinker over the four-seam. They also adjusted his arm motion to increase spin on his slider, allowing him to get more depth on the pitch. This change in hand allowed Zerpa to add some velocity on his sinker, with the pitch ticking up 2 MPH and getting more horizontal run.
The sinker became his primary pitch, and he leaned on that offering heavily, with sinkers making up 44% of his total pitches. He dominated early in the year, but struggles in August resulted in him being optioned to Omaha to build back his confidence. Zerpa returned to Kansas City in mid-September and did not allow a run in his 9 innings after his return. The Royals staff trusted him to throw four innings in the playoffs, where he only allowed one run.
Zerpa went into the offseason hoping to find more consistency and looked to carry the confidence he ended the year with into 2025. Again, the Royals made tweaks to Zerpa’s approach on the mound, adjusting his sinker grip and slowing down his slider. The sinker had a more consistent drop, but the most notable change has been to his slider, which has been a nightmare for opposing hitters this season.
The new slider from Zerpa has added five inches of vertical drop and two more inches of horizontal break. He struggled to locate the pitch early in the year, but since June has only given up two hits on sliders and hasn’t allowed a single hit off a slider in July. Now that he is a full-time reliever, Zerpa has all but eliminated the changeup and sticks to a sinker/slider mix with an occasional four-seam fastball.
Zerpa’s early struggles raised some concern, but he was able to polish things up and has been great as of late. Since May 17th, Angel Zerpa has thrown 25.1 innings, posting a 1.78 ERA and a 2.14 FIP while also getting 27 punchouts. His ERA is down to 3.70, and he is third among qualified pitchers in forcing ground balls, with a GB% of 67.8. Zerpa is sneakily having the best season of his pitching career, and his incredible transformation over the last several years is one of the Royals’ best success stories.