Non-MLB
Although they have not thrown an MLB pitch in 2024, Héctor Santiago threw 17,567 pitches that were tracked by the PITCHf/x system between 2011 and 2023, including pitches thrown in the MLB Regular Season, The World Baseball Classic and Spring Training. In 2023, they relied primarily on their Slider (80mph), also mixing in a Fourseam Fastball (85mph) and Curve (75mph).
In 2023, compared to other LHP:
Their slider has less than expected depth and results in somewhat more groundballs compared to other pitchers' sliders. Their fourseam fastball (take this with a grain of salt because they've only thrown 9 of them in 2023) comes in below hitting speed, is basically never swung at and missed compared to other pitchers' fourseamers and is an extreme flyball pitch compared to other pitchers' fourseamers. Their curve (take this with a grain of salt because they've only thrown 9 of them in 2023) has very little depth, is an extreme flyball pitch compared to other pitchers' curves, generates more whiffs/swing compared to other pitchers' curves, has primarily 12-6 movement and has slightly below average velo.