A look at the most dominant pitch used by every Mariners starter

Logan Gilbert - Slider

Usage: 29.7%
BA: .211
Whiff Rate: 32.2%
Strikeout Rate: 22.7%
Total Run Value: 15

2023 was the first year since his debut that Gilbert didn't have an exceptional four-seam fastball. Compared to 2021 and 2022, it regressed in nearly every category while his slider made huge strides. In particular, he increased his put-away percentage by 5% and his whiff rate by 7.1%. If you're interested in learning more, I wrote an article about this very pitch back in September.

Bryce Miller - Slider

Usage: 18.9%
BA: .202
Whiff Rate: 24.4%
Strikeout Rate: 26.0%
Total Run Value: 3

During Miller's strong rookie year, his five-pitch arsenal was well-rounded but the one pitch that stood out most was his slider. It averaged 86.6 mph and was his primary breaking ball option. He leaned heavily into his four seam fastball, using it nearly 60% of the time, so the slider was a welcome change of pace. He's allegedly adding a splitter in the offseason so expect him to continue attacking opposing batters below the zone in 2024.