We've got four young right-handed relievers who are performing well this season, Crow, Holland, Coleman, and Wood. I was looking at Fangraphs' pitch type chart, and I noticed they are all highly slider-dependent.
Wood throws only fastballs and sliders. Crow throws fastballs (60%), sliders (33%), and curves (7%), which means he could be a starter, you'd think. Holland has four pitches, a fastball (53%), slider (35%), curve (7%), and split-finger (6%). And Coleman has three, a fastball (53%), slider (41%), and an XX-ball (11%). Wonder what that is. Obviously, it's a none-of-the-above.
None of these guys throws a change-up.
Is this common? Do all young right-handed relievers throw lots of sliders? Is that why they're relievers and not starters? Collins, the young left-hander, throws a very different mix: fastballs (65%), curves (19%), and changes (17%).