Seattle Mariners
Although they have not thrown an MLB pitch in 2024, Jonathon Niese threw 18,891 pitches that were tracked by the PITCHf/x system between 2008 and 2016, including pitches thrown in the MLB Regular Season and the MLB Postseason. In 2016, they relied primarily on their Sinker (89mph), Fourseam Fastball (90mph) and Cutter (87mph), also mixing in a Change (83mph) and Curve (75mph).
In 2016, compared to other LHP:
Their sinker (take this with a grain of salt because they've only thrown 13 of them in 2016) has heavy sinking action, is basically never swung at and missed compared to other pitchers' sinkers and is an extreme flyball pitch compared to other pitchers' sinkers. Their fourseam fastball has heavy sinking action, results in more flyballs compared to other pitchers' fourseamers, has essentially average velo and has slightly less natural movement than typical. Their cutter has heavy sink, has sweeping cut action, generates a high number of swings & misses compared to other pitchers' cutters and is an extreme flyball pitch compared to other pitchers' cutters. Their change (take this with a grain of salt because they've only thrown 2 of them in 2016) is basically never swung at and missed compared to other pitchers' changeups, is an extreme flyball pitch compared to other pitchers' changeups and has some natural sink to it. Their curve (take this with a grain of salt because they've only thrown 10 of them in 2016) generates an extremely high number of swings & misses compared to other pitchers' curves, is an extreme flyball pitch compared to other pitchers' curves, has a sharp downward bite and has slightly below average velo.