The most unhittable pitch in baseball is back
https://www.mlb.com/news/shohei-ohtani-splitter-still-most-unhittable-pitch
Highest strikeout rate with a single pitch type, 2021
Minimum 20 PA ending on that pitch type
1) Shohei Ohtani's splitter: 90% (18 of 20 PA)
2) Tyler Glasnow's curveball: 68% (25 of 37 PA)
3) Dustin May's curveball: 67% (14 of 21 PA)
4) Cristian Javier's slider: 65% (13 of 20 PA)
5) James Karinchak's 4-seam fastball: 62% (16 of 26 PA)

Highest whiff rate with a single pitch type, 2021
Minimum 20 swings vs. that pitch type
1) Shohei Ohtani's splitter: 74%
2-T) Corbin Burnes' slider: 67%
2-T) Corbin Burnes' changeup: 67%
4) Raisel Iglesias' slider: 61%
5) Will Smith's slider: 61%