In the baseball world, there’s a tongue in cheek acronym used by prospect writers: “TINSTAAPP,” or “There Is No Such Thing As A Pitching Prospect.” The idea there is that young pitchers are highly volatile, developing in a frustratingly nonlinear fashion and subject to a myriad of devastating arm injuries. Pitchers, they say, will break your hearts.
But that’s not just true about young pitchers—it’s true about pitchers, period. Starting pitchers can go from zero to hero in a blink of an eye, and they can just as easily fall off a cliff for no apparent reason. Relievers are especially unpredictable, with high leverage innings magnifying their success or failures.