Non-MLB
Although they have not thrown an MLB pitch in 2025, Danny Duffy threw 20,752 pitches that were tracked by the PITCHf/x system between 2011 and 2024, including pitches thrown in the MLB Regular Season, the MLB Postseason and Spring Training. In 2024, they relied primarily on their Fourseam Fastball (91mph), also mixing in a Change (84mph), Curve (74mph) and Slider (80mph). He also rarely threw a Sinker (91mph).
In 2024, compared to other LHP:
Their fourseam fastball is straight as an arrow, results in more flyballs compared to other pitchers' fourseamers and has essentially average velo. Their change results in more flyballs compared to other pitchers' changeups and is slightly firmer than usual. Their curve has an exceptional bite, results in somewhat more flyballs compared to other pitchers' curves and has slightly below average velo. Their slider has exceptional depth, has short glove-side cut, has below average velo and results in somewhat more flyballs compared to other pitchers' sliders. Their sinker (take this with a grain of salt because they've only thrown 13 of them in 2024) is an extreme flyball pitch compared to other pitchers' sinkers, has surprisingly little armside run and has little sinking action compared to a true sinker.