Let’s All Aroldis Chapman
It can be difficult to write up some moves. For example, when one great reliever takes over a high-leverage role from another great reliever in the midst of having some bad luck, it seems there’s little to say. Sean Marshall is good, but Aroldis Chapman is better. Done?
Sean Marshall has a 1.42 xFIP based on a double-digit strikeout rate, a minuscule walk rate, and a great ground-ball rate that should lead to a better home run rate than he’s showing now. Aroldis Chapman has a 1.53 xFIP based on a double-digit strikeout rate, and above-average walk rate (right now), and an average-ish ground-ball rate that has been better over his career. What he does have, that Marshall doesn’t, is the velocity of a closer. Still humping it over the plate above 97 MPH, he has some of the best gas in the game.
But that doesn’t mean there aren’t some hurdles for him to overcome on his way to being a lights-out closer.

