The pitchers we're looking at here aren't necessarily the game's best, and their key pitches aren't necessarily the best of their type. These are pitchers with upside who -- with a tweak or two -- could markedly improve their performances this season. But they each have a "problem" pitch that could prevent them from reaching their upside, including one with a pitch he is so totally reliant upon that it needs to be supplemented for him to thrive or survive long-term.
I'll be referring to contact scores throughout this article, which is the relative production allowed by a pitcher overall or on a given pitch -- 100 equals the league average, and a figure less than 100 is better than league average; more than 100 is worse.