Tom's Pitching Lab: Lowering the Arm Angle Is Changing What MLB Pitchers Throw, Not Just How
Tom's Pitching Lab: Dropping the Arm Angle Works and How Logan Gilbert's 2026 Proves It, In Reverse
Logan Gilbert spent three years lowering his arm angle and getting better each time. Emerson Hancock spent two years doing the same thing, and this season he took the final step down to a slot Gilbert was approaching but never reached. Both men running the same experiment, on different timelines, converging toward the same conclusion.
Then Gilbert stopped. This offseason, he told reporters he had worked on his mechanics specifically to raise the slot back up, because he believed the lower position was a flaw in his delivery. Gilbert raised his arm slot on purpose. He thought he was getting better.
His underlying numbers in 2026 say otherwise. And the contrast between what happened to him and what happened to Hancock is the clearest explanation of what the arm angle drop actually does - and what walking away from it can cost you.
What Changes When the Arm Goes Down
The arm angle drop trend accelerated after Baseball Savant published its arm angle leaderboard in 2022, giving pitching coaches the first publicly available tool to track, benchmark, and deliberately replicate what had previously happened by accident. Organizations like the Mariners built it into a coordinated system - and the number of pitchers dropping five or more degrees from one season to the next has climbed every year since. That is what makes 2026 different from 2016.
What we are still learning, though, is how the body actually adjusts to throwing from a new slot - and the data keeps humbling early assumptions. The first season is rarely a transformation. It is closer to an audition, with the pitcher learning to repeat a release point that feels foreign, command lagging behind intent, and results swinging wildly from start to start. The mechanism is real. The adjustment is also real. The pitchers who come out the other side are the ones who stayed with the discomfort long enough to make the new slot feel like home.
The first thing that changes is not the fastball. It is the breaking ball.
When a pitcher lowers the arm angle meaningfully - five degrees is the threshold worth tracking - the spin axis on sliders and sweepers shifts, adding horizontal movement (side to side) and reducing vertical (up and down) drop. Drop far enough and you unlock the sweeper from a grip that physically could not throw one from the old slot.
The fastball changes too, arriving at the plate from a new angle, but hitters adjust to a new fastball plane faster than they adjust to a reshaped breaking ball. The breaking ball is generating whiffs hitters haven't yet learned to lay off. That window - between when the pitcher changes and when hitters catch up - is where the fantasy value lives.
Gilbert's Blueprint, and Hancock's Execution of It
Gilbert's arc: 52.3 degrees in 2023, down to 43.8 in 2024, down to 40.2 in 2025. Each year the slot dropped, the profile improved. His 2025 season, despite missing significant time to an elbow injury, was the best of his career: 11.9 K/9, 15.5 percent SwStr%, a 3.08 xERA. The lower slot was not a coincidence. It was working.
Hancock's arc: 27.5 degrees in 2024, 18.5 in 2025, roughly 12 degrees in 2026. Like Gilbert, Hancock was dropping his slot each season, but lower than 97 percent of right-handed starting pitchers. The pitch data shows what that unlocked: his sweeper usage jumped from 3 percent to 25 percent. A breaking ball class with zero above-average run value in 2025 posted a mark of 24.4 runs above average in 2026. He did not refine an existing pitch. The lower slot made a new one physically possible, in the same way a door you could not open from one angle swings freely from another.
His ERA is 2.74. His K/9 is up 2.3 strikeouts per nine innings. Those are real. His xERA is 4.37 and his hard-hit rate climbed from 42.5 to 44.9 percent. That is also real. The new breaking ball is missing bats at rates the old one could not. The fastball from the new angle is getting squared up more than it used to. Both things are happening at once, and the ERA reflects whichever one happens to show up in a given game. Hold Hancock for the strikeouts. Do not trust the ERA.
The 2026 Droppers, With Gilbert as the Counterpoint
Thirteen pitchers dropped five or more degrees from 2025 to 2026. Five have enough innings to evaluate. Gilbert sits in the table highlighted - he raised his slot and his numbers deteriorated in the exact ways the mechanism predicts. The comparison is the point.
Hancock and Cade Cavalli are the ones doing what the mechanism predicts: K/9 gains of more than two strikeouts per nine innings, ERAs running well below their xERAs. The strikeouts are real. The ERAs are not. Ryan Weathers gained a modest strikeout per nine innings and his ERA and xERA are close together, which means the adjustment is largely behind him - stable, not exciting, not a trap.
Freddy Peralta's K/9 fell despite the drop, which looks bad until you remember he was already at 10.4. His xERA (3.81) is better than his ERA (4.04). Positive regression coming, independent of the slot.
Mike Burrows (now with the Astros) dropped the most - 8.8 degrees - and produced the worst results. K/9 fell from 9.1 to 7.4. His ERA is the highest among qualified starters. xERA at 4.66 is not coming to the rescue. The arm went down and the breaking ball did not follow. The mechanism creates the opportunity. The pitcher still has to develop the pitch.
What Gilbert's Numbers Actually Say
When Gilbert raised his slot this offseason, he did it to throw a better cutter. He told reporters that his old lower slot was the result of his hips pulling his arm down involuntarily - that staying closed and firm on his front side put him in what he called a better spot. He was fixing a problem he had identified. Reasonable. Intentional. And, per the data, a mistake.
K/9 fell from 11.9 to 9.3. SwStr% from 15.5 to 13.0 percent. Hard-hit rate from 41.7 to 45.8. Barrel rate from 8.6 to 11.6. Every metric the lower slot had been improving moved the wrong direction when the slot went back up. His ERA is 3.62 and his xERA is 4.08, with a strand rate that is holding the ERA below where the contact quality says it should be. But the combination of slot reversal, a 2025 elbow injury early in the season, declining whiff rate, and rising contact quality does not point at a pitcher whose ERA is going to stay at 3.62. Sell him if you can get fair value.
Two Names to Target
Ian Seymour dropped 6.2 degrees and his SwStr% rose from 12.1 to 13.6 percent - the best whiff rate in the dropper group. His xERA is 3.64. His ERA has been all over the place, partly because of a disastrous Opening Day outing and partly because the walk rate jumped from 3.0 to 4.1 BB/9 after the slot change.
Command is typically the first thing to deteriorate when you change your release point and the first to recover as the new mechanics solidify. One role caveat: the Rays have been using Seymour as an opener and bulk reliever rather than a traditional starter, so he accumulates innings and strikeouts in pieces rather than a clean five-to-seven inning line. The fantasy value is real. It just comes in an irregular shape. If you are in a format that counts strikeouts and ERA regardless of role, he is worth adding at his current availability.
Jesus Luzardo barely changed his slot, so the arm angle story does not apply to him. But he belongs here because his hard-hit rate fell from 37.1 to 28.9 percent, one of the steepest contact-quality improvements among qualified starters in 2026, and his ERA (4.35) reflects a BABIP that is tracking well above what his underlying contact metrics support. His xERA is 3.43. The ERA will come down. Buy him.
The Bottom Line for Fantasy Owners: The Three Step Process
Tom's Pitching Lab is all about usefulness, not just about mind-bending mathematics.
Step one: Check out the Baseball Savant arm angle leaderboard. Confirm the pitcher dropped at least five degrees from their prior-year angle. If they moved the other direction - or barely moved at all - they are not part of this trend, regardless of what the podcast says.
Step two: K/9 year over year. A gain of at least one strikeout per nine innings means the new breaking ball is generating whiffs. The mechanism is operational.
Step three: ERA versus xERA. K/9 up and ERA running below xERA means the strikeouts are real and the ERA will rise toward xERA as the contact quality catches up. Hold for the K/9. Manage expectations on the ERA.
The Gilbert corollary: Raise the slot, lose the whiffs, ERA looks fine, LOB% is doing the work, xERA says it won't last. The mechanism runs the same direction whether the slot goes down or up. Check the arm angle leaderboard monthly. The adjustments keep coming and the window between when they happen and when they show up in results is consistent enough to trade on.
Questions About Arm Angles, Answered
How does lowering your arm angle affect breaking balls?
Drop the arm five degrees and your slider stops being a slider - it starts being a sweeper your hitter has never seen before, and that is the entire ballgame.
Why do pitchers who lower their arm angle sometimes allow harder contact?
The new breaking ball fools everyone, but the fastball is coming from a weird new address hitters haven't learned to ignore yet, so they hit it hard while they figure it out.
What is the screening signal for arm angle drops worth acting on in fantasy baseball?
Three steps: Confirm the drop on Baseball Savant, confirm K/9 is up at least one strikeout per nine, then confirm ERA is running below xERA - all three or you're just guessing.
What happened to Logan Gilbert when he raised his arm slot in 2026?
He fixed a mechanical flaw he identified, his K/9 fell 2.6 strikeouts, his hard-hit rate jumped four points, and his ERA is a 3.62 held together by strand rate - sell him before the bill comes due.
Why is Jesus Luzardo's ERA misleading in 2026?
His hard-hit rate dropped nearly nine points, his xERA is 3.43, and his ERA is 4.35 - the gap between those two numbers is a buy signal, not a warning.
Can an arm angle drop backfire in fantasy baseball?
Ask Mike Burrows, who dropped his slot 8.8 degrees, watched his K/9 fall anyway, and now owns the highest ERA among qualified starters - the door only opens if you can actually throw the pitch.
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This story was originally published June 17, 2026 at 12:28 PM.