Coming into 2021, Michael King was not necessarily envisioned to be a big part of the Yankees’ bullpen. A 2016 Miami Marlins draftee, King came into spring training with just 28.2 major league innings under his belt, all with the Yankees and mostly in the shortened 2020 season. While his 2021 season, like much of the Yankees’ season, was up and down, King nonetheless showed growth and promise that the Yankees should hope to build on in 2022.
King made the major league roster out of spring training and immediately caught eyes – in his first appearance of the season on April 4, he tossed six scoreless innings in relief of Domingo German in a 3-1 loss to Toronto. Efficient and effective in that outing, he used only 68 pitches to get through the fourth through ninth innings, giving up one hit and striking out three.
He was optioned to the Alternate Site (RIP Alternate Site) after that outing, and after each of the two additional appearances he made for the major league club in April in more typical middle-relief roles. Despite logging frequent flyer miles throughout the early part of the season, King continued to impress, throwing 11 scoreless innings before giving up his first run of the season on May 13.
Throughout the season as the bullpen suffered a variety of slumps and injuries, King came to be relied on as a versatile swing-man, becoming a peripheral member of Aaron Boone’s circle of trust. Between the end of May and the end of June, he was thrust into a spot-starter role, where he made six consecutive starts that could be best described as “mostly serviceable.” His overall 5.47 ERA as a starter was impacted by an oddity; he pitched to a bloated 15.00 ERA in the first inning, but would typically settle down thereafter, sporting a 2.63 ERA in innings two through six.
As with many baseball statistical outliers, it’s unclear why King struggled so much in the first inning while putting up good numbers afterwards, but after he missed over a month with a finger injury (he allegedly jammed his finger between plates during a weightlifting session, go figure), he returned to action on September 10 in a strictly relief role. He thrived over the last month of the season, putting up a 1.23 ERA over 14.2 innings in the month of September, striking out 14 and walking just 3. While his innings were limited, his success in September indicated that, had the Yankees progressed further into the playoffs, he was going to be a central figure in their bullpen.
King has always been a sinker-heavy pitcher, and he continued that trend in 2021, but one of the major reasons for his growth during the year appeared to be significant change in the horizontal break of his slider (as documented by Lucas Apostoleris and Eno Sarris), which became a strong secondary pitch for him throughout the season. He reportedly came into the season with a goal of making his slider “more sweepy”, and enlisted the help of veteran Corey Kluber in pursuit of more side-to-side movement on his breaking pitch.
His slider became a great weapon for him in 2021, as he put up a 28.8% whiff rate on that pitch. Combined with a and maintained solid strikeout numbers (8.8 K/9 rate through 63.1 innings). He also added velocity to his four-seam fastball and sinker, increasing his average speed from 2020 by a full 1.5 mph on the four-seamer, and by nearly a full mile-per-hour on his sinker, which he threw over 50% of the time this past season.
What is clear from his 2021 performance is that King is still figuring out what pitch mix works best for him, but his tools are good enough for optimism going forward. The Yankees have reason to hope that King will continue to be a strong figure in the bullpen moving into 2022, as he looks to repeat the success he had late in this season. He could also have proven himself valuable enough to be trade bait in the offseason if the Yankees decide that their needs are greater in areas other than the bullpen. Either way, King’s progression in 2021 adds value to the team that fans should be excited about.