Seattle Mariners: Paul Sewald and what we can expect in 2022

One of the most unlikely stories in 2021 was a funky right-hander signed to a minor league contract before Spring Training. His season was almost too unbelievable and it would seem difficult to repeat. Paul Sewald was a revelation in Seattle in 2021… can he come close to repeating in 2022?

Let’s start with the changes he made to his physical stuff and command. Sewald attributes much of his success to the Mariners pitching department, and his decision to switch to a Fastball/Slider mix only made him a strikeout machine. An increased focus on creating two dominant pitches, as well as a focus on executing those pitches made him one of the most dominant relievers in baseball in 2021.

Paul Sewald is poised for a big role in the Mariners Bullpen in 2022

Let us begin with his fastball. While only ranking in the 33rd percentile in velocity, Sewald’s fastball ranked in the 90th percentile in spin rate according to Baseball Savant. Pair this in with attacking the upper part of the zone, creating an almost untouchable pitch. Because the fastball rides through the zone, the hitters have a hard time deciphering its depth to their eyes, causing them to swing underneath.

With the help of the Mariners coaching staff and a consistent focus on commanding the top part of the zone, Sewald should be able to repeat success with his fastball as long as his spin rates remain up.

His career-altering 2021 was bolstered by a devastating slider. Sewald attributed a lot of his success with his slider to a switch in thinking, instead of trying to create depth trying to create more horizontal movement moving away from the batter. In turn, this created a 43% whiff percentage according to Baseball Savant. His slider moves 3.3 inches more horizontally than the average MLB slider. Straight filth. As long as this pitch keeps its movement profile similar to 2021, it will continue to generate plenty of swings and misses.

There are a few reasons to believe regression could be on the horizon, however. Zips projections believe Sewald will finish 2022 with a 3.82 ERA and a 3.54 FIP with 83 Strikeouts in 63 innings. That comes out to a K/9 of 12.4 and a K% of 33.7% for the season. For reference his 2021 finished with a 14.5 K/9 and a K% north of 39% according to Baseball-Reference. These numbers are almost certainly not sustainable, so I would tend to agree with ZIPS on these projections.

Although Sewald threw 64 innings in 2021, he was clearly fatigued by the end of the year. Being called up in May and throwing that many innings are almost unheard of. This led to his sparkling ERA rising above 3 at the end of the year. With more bullpen depth and more trusted options outside of Steckenrider, Castillo, and Sewald, the hope would be that Sewald can be more effectively managed to avoid burnout in 2022.

So can Paul Sewald repeat his 2022 performance? The short answer is yes, with execution and his physical stuff remaining intact. Although his numbers are unlikely to be as impressive as 2021, even with regression he should be an impressive pitcher and a key contributor for the Mariners in 2022. I would believe Sewald’s performance will be somewhere in between his 2021 numbers and 2022 projections.

Long live Paul Sewald.