
Jonathan Loáisiga has been one of the best relievers in baseball this year. He leads all bullpen arms with 2.4 fWAR and his 66.2 IP have been crucial to the Yankees’ success this year. This tremendous success might come as a surprise to some, but Jonathan has been steadily building towards this breakout over the last few years. Before we examine how he has improved, let’s take a look at how he got here.
Early Career
Loáisiga was signed as an international free agent by the San Francisco Giants in 2012 as an 18-year-old out of Nicaragua. He dominated the Dominican Summer League in 2013, but injuries prevented him from playing professional ball in 2014 and 2015. After a release from the Giants, Jonathan signed with the Yankees in 2016 and was sent to single A ball. Things didn’t go as planned, and Loáisiga needed Tommy John surgery after just 2.1 IP in the Yankees system. After a full recovery from the surgery, Jonathan once again dominated in 2017. In the Gulf Coast League and with the Staten Island Yankees, he sported a 1.38 ERA across 11 appearances.
Making It Major
In 2018 he graduated from A to AA where he continued to impress, striking out 40 batters in 34.1 IP. An injury to Masahiro Tanaka in June gave Loáisiga his first taste of the majors and he made his MLB debut on June 15th, 2018. He pitched 5 scoreless in his debut, but he finished the 2018 campaign with a 5.11 ERA in 24.2 IP. While the traditional statistics weren’t great he still had 12.04 K/9 and a 3.53 FIP, which were encouraging. Jonathan broke camp with the Yankees in 2019, but he dealt with some injuries and spent most of the year going back and forth between the Majors and AAA. When he was with the Yankees, Loáisiga pitched to a 4.55 ERA over 31.2 innings, but he continued to show improvement. Due to the shortened season, Jonathan only pitched 23 innings in 2020, but he began to emerge as a reliable option for the Yankees. He ended the year with a 3.52 ERA, 1.22 WHIP, and 22 strikeouts in his limited work. Loáisiga was also in the 95th percentile of MLB players in both Average Exit Velocity and Hard Hit Percentage. After showing constant improvement, he has been trusted with a high-leverage role in the Yankees in 2021. Jonathan was a good pitcher before this year, but he has made some adjustments in pitch usage and location that have made him truly great.
Taking A Step Forward
Throughout his career, Loáisiga has used a four pitch mix that includes a 4-seam fastball, a sinker, a curveball, and a changeup. Like a lot of today’s relievers, he is a flame thrower and he regularly sits in the high 90’s with both his fastball and his sinker. To play off of his high velocity, he throws his hard changeup around 90 mph and a sharp breaking curve that is usually in the high 80’s. Jonathan has also had a bit of a velocity bump this year that has made his pitches even more effective. His stuff has always been good, but he is now using it differently and locating his pitches more favorably.
The most significant change Loáisiga has made this year has been in the usage of his sinker and his fastball. In 2020 he threw his sinker 24.6% of the time and that number has more than doubled this year up to 54.4%. Conversely, his fastball usage has fallen from 42.6% in 2020 to 4% in 2021. With this change in usage has come a change in strategy that has led to some better pitch locations as well. Jonathan often uses his sinker down and in to right handers and down and away to lefties, which creates a lot of weak contact and ground balls. In 2021 he has thrown his sinker either in the zone or running out of the zone so it ends up as a very tempting ball. Instead of his primary pitch, Jonathan’s fastball is now more of a swing and miss option that plays off of his sinker. The locations of his fastball this year have primarily been in the middle to upper part of the zone or up and out of the zone. His change in usage has made both of these pitches better because the sinker is producing more ground balls and his fastball is producing more whiffs.

Loáisiga has also bumped up the usage of his changeup and his curveball in 2021, but he has improved these pitches by executing his locations more effectively than in the past. Jonathan has done a much better job of keeping his changeup down this year, which along with his increased sinker usage has produced a career high GB% of 61.5%. He has also been throwing his curveball more consistently which has led to an increase of almost 5% in his Whiff% this year. Loáisiga has been keeping his curveball down and away to righties and down and in to lefties, but this year he is forcing batters to swing at more of these pitches. He has mostly stayed in that area, but he is in the zone more often, and closer to the zone when he misses.

A Bright Future
When you combine great stuff with great execution, you get great results. In 66.2 IP this year, Loáisiga has a 2.16 ERA, a 2.41 FIP, and a 2.95 SIERA with 65 K’s. His GB% of 61.5% combined with an 8.78 K/9, a 0.27 HR/9, and a 1.04 WHIP is a formula that is clearly working. In August, Jonathan had the best month of his career, sporting a sparkling 0.63 ERA in 14.1 IP. Moving forward, Jonathan should continue to see a lot of high leverage situations for the Yankees and he will be an important piece of their bullpen in October. If Aroldis Chapman struggles at any point it would not be a surprise to see Loáisiga in the closer role either. At just 26, Jonathan has a very bright future in Major League Baseball if he continues to work hard and hone his craft.