Airsoft pellets are cheap balls and some people do it competitively.
I suspect that knuckleballers, in particular, were the pitchers prized getting a scuffed ball, as any scuff or foreign substance on a knuckleball will enhance the unpredictable nature of its movement.
But, and probably not coincidentally, the knuckleball has died out as a major-league pitch. When I was in high school and college, in the late 1970s and 1980s, and first really getting into baseball, there was still a handful of well-known knuckleball pitchers still in the game: Gaylord Perry, Phil and Joe Niekro, Charlie Hough, Wilbur Wood, and by the '80s, Tom Candiotti. Most of them were also known for (or strongly suspected of) doctoring the ball with Vaseline, scuffs, etc.
Since then, there’s only been (AFAICT) four MLB pitchers who’ve made a career out of throwing the knuckleball: Tim Wakefield, Steve Sparks, R.A. Dickey, and Steven Wright; there hasn’t been a single pitcher who regularly uses the pitch, and has had any kind of an MLB career, since 2019, when Wright last played.
Thank you for that! Now I have something more to talk about with my BIL from Perth.
That’s pretty low.
How much does a cornhole bean bag cost?