The Straightest Fastballs
We do have leaderboards for this sort of thing, but the problem is that if you’re looking at horizontal movement, PITCHf/x data for lefties and righties is very different. For example, the average four-seam fastball for a lefty goes 91 mph, but breaks +5.5 inches. The average four-seam fastball for a righty goes 92.2 mph and breaks -4.2 inches. So if you sorted one way or the other for horizontal fastball movement, you would just be getting the best lefties and righties.
So I did the work for you. Voila, the straightest fastballs in the game. It may be the least important facet of a fastball, behind location and velocity, but it’s still a facet we don’t talk about much.