Although they have not thrown an MLB pitch in 2023, Kervin Castro threw 1,099 pitches that were tracked by the PITCHf/x system between 2021 and 2022, all of them occuring in the MLB Regular Season. In 2022, they relied primarily on their Fourseam Fastball (93mph) and Curve (79mph), also mixing in a Slider (83mph) and Cutter (89mph). He also rarely threw a Change (90mph).
In 2022, compared to other RHP:
His fourseam fastball is straight as an arrow, generates a high number of swings & misses compared to other pitchers' fourseamers and has essentially average velo. His curve has an exceptional bite and has primarily 12-6 movement. His slider has exceptional depth and is an extreme flyball pitch compared to other pitchers' sliders. His cutter has heavy sink, is a real worm killer that generates an extreme number of groundballs compared to other pitchers' cutters, has sweeping cut action and generates more whiffs/swing compared to other pitchers' cutters. His change (take this with a grain of salt because he's only thrown 1 of them in 2022) is thrown extremely hard, is basically never swung at and missed compared to other pitchers' changeups, results in more flyballs compared to other pitchers' changeups and has slight cut action.