Finding the Red Sox Next Breakout Reliever: Justin Garza Has Great Stuff

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Justin Garza's stuff is playing at the MLB level.

Relief pitchers come in all shapes and sizes. From Reyes Moronta to Sean Hjelle and everything in between. Some throw 100 MPH cutters (Emmanuel Clase), and others throw nothing but sliders (Austin Adams). There's no "right" way to pitch out of the bullpen. Pitching for just an inning or two, just one quality pitch can be enough to get by. That's why it sometimes may feel like you can pull a random person off the street for a shutout appearance.

Last week, I wrote about how the Red Sox bullpen needs a shakeup. With Chris Sale going to the IL and Kutter Crawford headed back to the rotation, someone has to step up. That's where Justin Garza comes in. Since being acquired from the Angels, Garza has thrown nine innings across eight games with a 1.00 ERA and eight strikeouts. Solid numbers, but it's fair to say many of the innings were low-leverage.

Looking past the surface level results, there's another major reason to believe Justin Garza can become a stable reliever. As I tend to say with every pitcher I dive in on, it all starts with the fastball. Garza's "sinker" accounts for about 50% of his pitches and is his primary weapon. I put sinker in quotations, because it really isn't a sinker. It has the movement of a four-seamer and Garza throws it up in the zone like a traditional four-seamer.

If it moves like a four-seamer and it's used like a four-seamer, it's probably a duck. I mean four-seamer. If you don't believe me, take a look:

According to Alex Chamberlain's research on vertical approach angle, sinkers perform best when they’re "steep", while fastballs perform better when they’re "flat". Garza throws an incredibly flat "sinker". His fastball ranks 11th in terms of vertical approach angle above average in the entire MLB, most of the pitches ahead of him in the rankings are from submarine and sidearm arm slots, making his VAA AA all the more impressive.

Without getting too in the weeds, the flat fastball helps his fastball play up in the zone and helps limit damage when a pitch catches too much of the plate. He doesn't have crazy velocity, but the shape of the pitch makes it a legitimate weapon. He needs more than just the fastball to be consistently great, but it's the backbone of a strong reliever.

It's also worth noting that the vertical approach angle represents something of a trend for the Red Sox front office. John Schreiber and Hansel Robles both have exceptionally flat fastballs. Wyatt Mills, while he's yet to pitch in the majors, is a John Schreiber clone. While there have been mixed results, it's good to see the Red Sox follow some sort of organizational philosophy and try to capitalize on a relatively new development in pitching.