Yeah, that lack of strikeouts for a guy who throws harder than anyone else in baseball is definitely weird.
For one thing, it probably points to a unique quirk with his career: he pitched most of last season at low A-ball. He got an August promotion to A+, but he’s never played AA or AAA. He looks at times very much like a 21 year old pitcher who was drafted out of high school…which is what he is.
The other thing: he has a slider. When he can throw it for strikes, it’s a very good one. But…his numbers suggest that at this point in his career, he’s very likely telegraphing both his fastball and slider in his delivery, so hitters can tell what’s coming.
Finally: the most amazing thing about Jordan Hicks and his 105-mph pitches and the lack of strikeouts is this. He’s not throwing 4-seam fastballs. Those have “ride”, meaning they basically sit on a fairly level plane as they approach the plate, giving the illusion that the pitch rises (physics says that’s impossible). That’s why the 4-seamer is still the ultimate strikeout pitch, though. Because it rides the way it does, it typically comes in faster than any other pitch (something about the spin rate and seams) and also creates a very brief intersection of the plane of the ball and the plane of the bat.
A 2-seam sinker (which is what Hicks throws) is typically a slower pitch than a 4-seamer (again, something something seams and spin), and has sharp, late downward movement that also runs slightly arm-side for the pitcher. That puts it right into a situation where it creates a much larger intersection of the plane of the ball and the plane of the swing. Although some pitchers have effectively used a 2-seamer for strikeouts (Greg Maddux), for most pitchers it is a contact pitch, one that hitters typically struggle to lift. It’s a ground ball pitch, a double play waiting to happen.
Jordan Hicks may not get a lot of strikeouts (yet), but he sure gets a TON of ground ball outs. If they decide they want to see him miss more bats, they may teach him the 4-seam fastball. Which is weird that he doesn’t throw one, because that’s typically the first pitch you learn in little league.
As a final illustration of the quirk of Jordan Hicks and his sinking fastball, I offer a comparison with former Cardinals closer Trevor Rosenthal. Rosey also threw hard, often touching triple digits. Rosenthal’s fastball was a 4-seamer. And he struck a lot of guys out. But you can count on the fingers of both hands the number of GIDP Rosenthal got in his years as St. Louis’s closer. (A quick check: Rosenthal on average induced about 4 ground ball double plays per season as the Cardinals closer; in 2014 he had his best year at that, getting 8 double play balls in 80 opportunities, a 10% rate).
Hicks, meanwhile, has induced 6 double plays already this season in 29 opportunities, a 21% rate.