Amidst a quiet offseason, the Minnesota Twins claimed righty reliever Zack Weiss off waivers. It’s a minor move, but it reflects a larger idea. MLB teams should be acquiring players like Weiss.
Weiss has only pitched 27.1 big league innings in his career, and his 97 ERA+ and 6.44 FIP don’t inspire confidence. However, Weiss has electric stuff. His 94 mph four-seamer gets an elite 18.3 inches of induced vertical break. A good Vertical Approach Angle (VAA) isn’t a requirement for success, but Weiss’s 0.44 degrees more than expected (from his arm slot and release point) should theoretically help him.
The pitch teeters on the edge of the cut-ride/cut-carry variety, like Josh Staumont’s four-seamer. Weiss’s 4.4 inches of arm-side movement is inches away from the arbitrary cut-ride threshold of 3 inches. Suppose the Twins and Weiss alter his four-seamer’s shape into more cut-ride. That would allow him to mess with a hitter’s brain and eye as they watch how Weiss’s four-seamer doesn’t move the way most other MLB pitcher’s four-seamers do.
Regardless of how the pitch shape looks heading into the season, it grades well by Stuff+. Stuff+ is a metric that aims to measure the quality of a pitch based on velocity, spin, extension, and release point, among other factors. For consistency, I’ve derived all the following Stuff+ numbers from Jeremy Maschino’s MLBPitchProfiler.
Weiss’s 109 Stuff+ four-seamer mark is similar to Griffin Jax’s 116 and Staumont’s 104. But the rest of Weiss’s arsenal separates him from other relievers. His slider and cutter earned Stuff+ grades of 116 and 134, respectively. Weiss’s slider and cutter boost his overall Stuff+ grade to 114, good for 89th percentile.
Stuff+ is more than just another way to measure a pitcher’s ability. Pitching+ combines Stuff+ with Location+, a measure of the quality of the pitch’s end location. Pitching+ predicts a reliever’s future ERA better than any other stat. The same is true for starters. However, it’s more reliable for relievers.
A pitcher’s command is far more difficult to maintain start-to-start and year-to-year than stuff. Since relievers pitch in small sample sizes in each game and season, they must have good Stuff+ numbers. In the chaotic world of relief pitching, teams should build their bullpen on a solid analytical foundation. Minnesota has taken that idea in stride this offseason.
Staumont, Justin Topa, Steven Okert, and Matt Bowman grade out as above average in Stuff+. Staumont and Bowman’s 101 Stuff+ is in the 52nd percentile. Okert’s 103 jumps up to the 62nd percentile. Topa is the best of the bunch at 117, 92nd percentile.
They may lose command and grade out poorly in Pitching+, the stat with great predictive power. But at least they’ll have a solid base in Stuff+ to build upon.
We should highlight that the goal of building a bullpen isn’t solely stocking up on high Stuff+ arms. Each pitcher has a unique skill set and game plan. Minnesota’s coaching staff won’t rest on their laurels knowing they’ve acquired quality Stuff+ relievers. Weiss, Staumont, and Bowman have made pitching adjustments recently or could improve with one.
Weiss shifted closer to first-base from the third-base side of the mound between his appearances in May and July. Perhaps he wanted his sliders to start over the middle of the plate more before tailing off rather than starting inside.
Bowman added a sweeper and cutter sometime before last season, filling out an extreme east-west approach. Staumont may not need to alter the shape of his four-seamer, but a slight change in the orientation of his hand at release could pay large dividends.
The Twins may ultimately have an uneventful offseason, but they’ve quietly built up a reliable bullpen.
