This is where art meets science when determining what to do with arm path.
In our video meeting, Tyler shared a biomechanics report of an amateur pitcher training with us. Tyler directs my attention to the pitcher’s posture metrics, which includes measurements and line charts of different components of the athlete’s throwing motion.
“‘Torso side bend at foot plant,’ that’s basically how far I’m tilted this way,” said Tyler of this particular measure, tilting his right shoulder toward the third-base side at release to mimic a left-handed thrower. “We generally want to be as high up on the Y axis. … The more side bend we create, the more velocity we create.”
But more side bend also corresponds with raising a release point.
Tyler notes this athlete ranks in the 52nd percentile of side bend at foot plant. Our software calculates it’s costing him 0.04 mph. Is it worth altering his release point?
“If we move him all the way to the right (on the Y axis) is it a full (mph)? Is it only four-tenths?” Tyler said. “It’s kind of individually specific, but these are the variables that we try and talk and think about when we make decisions in regard to adjusting arm angles.”
Another consideration is how lowering an arm slot can affect movement profiles.
Tyler notes how as a lefty, if he lowers his slot the direction of finger placement changes from nearer 12 o’clock, with a more over-the-top release, to nearer 9 o’clock. Such a change would have a dramatic effect on movement profiles.
“It all has to be taken into consideration,” Tyler said.
One of the most effective lower-slot movement profiles is, again, the high-efficiency fastball with a flat approach angle, the signature trait of Woo and Ryan.
But that requires a pitcher to have enough radial deviation, or wrist mobility, to create the right seam orientation at throwing release. In other words, more active spin – efficient spin. True backspin.
Ryan’s four-seamer features 97% active spin from that slot last season. That’s almost perfect spin efficiency. Woo’s active spin also above-average at 91%, rare from such a slot.
“If I can lower your slot and radial deviate your hand when you throw, and maintain your IVB, then we’re probably looking at creating something close to an outlier fastball,” Tyler said.
Not everyone has such mobility.
However, one way to hack the lower slot for a pitcher unable to maintain high active spin is to throw a cutter from that position. “You can have that more aggressive VAA and still generate some lift,” Tyler said of throwing a cutter from such a slot. A high-ride cutter is effective on its own, Payton noted, but like a four-seamer that can maintain its efficient spin from a lower slot, a cutter can enjoy similar benefits.
There are additional benefits of lowering slot beyond adding deception, the riding effect of a fastball.
While velocity generally declines with slot angle, pitchers who lowered their slot over the last decade gained spin.
Consider in the two most recent seasons studied, 2024 and 2025, our sample of 226 MLB pitchers gained, on average, 18.3 rpm on their four-seam fastball. This was despite velocity loss.
Lowering slot doesn’t guarantee success but when it does work, it can be significant.