The thoroughly modern baseball fan knows what a frontline starter looks like.
He’ll throw a high-spin four-seam fastball at the top of the zone, getting it up above the hitter’s hands and racking up whiffs and lazy fly balls. Or maybe he’ll throw a wake-shifted sinker in under the hitter’s hands, getting whiffs and weak contact. He’ll pair one or more breaking pitches with mirrored movement planes off that primary offering.
Modern pitching optimization is directional — pitches are located where their movement plays up, and pitch systems work together to make the batter wrong in opposite and complementary directions.