Breaking down the splitter, the least-popular pitch in baseball
This all speaks to the versatility of the splitter. It's a more challenging pitch to master than a changeup, and has the same downside; if a pitcher leaves his splitter up, it's probably going to travel a long way. It has a bit more pace than a changeup and, importantly, as the same rotation as a four-seam fastball. And, as Tanaka, Samardzija and Hudson prove, so long as a pitcher commands the pitch and gets a wide enough margin between his heater and his splitter, it can be a filthy out pitch.