Pitch Development and Design… The Elusive Cutter – Part 6

By Bahram Shirazi (BSEE, MBA, Co-Owner RPP)
Robbie Aviles (Pitching Lab Coach)

Today’s article is on cutters, the same pitch Mariano Rivera made a nice living with, even though his opponents knew it was coming nearly 90% of the time.  Cutters or cut-fastballs move differently than every other fastball.  But before we go any further let’s establish what we consider to be a cutter and there is no better place to go than Rivera’s pitch…

Let’s quickly look and see how his cutter behaved.  Here are his average metrics for his final 5 years:

    • Average Velocity: 92 mph
    • HB: -2.4 in (Pitch/Fx)
    • VB: +7.2 in (Pitch/Fx)
    • Spin Axis: 153 degrees (Pitch/Fx)

We should note that Pitch/Fx data isn’t necessarily comparable to Rapsodo (which is what we use here at RPP), but we can draw some basic conclusions.

Spin Axis – The following diagram might be a bit confusing, but it helps us convert his spin axis degrees from Pitch/Fx to the Rapsodo clock.  Assuming a simple conversion is possible, a spin axis of approximately 155 degrees would imply a Rapsodo spin axis of 11:15-ish.

Movement – His cutter movement was more “up” than it was “away”, which implies he had more back spin that lateral spin.  But nonetheless its lateral movement was glove-side, which brings us to what we mean by glove-side.  Some think of it as movement to the left of a righty’s fastball.  We don’t consider that glove-side.  We believe glove-side to be movement that has a negative lateral trajectory against the vertical line at the gyroball.

Now let’s review where a cutter might sit on a typical movement chart.  Given its proximity to the slider and gyroball, it will undoubtedly have spiral spin, but less so than a typical slider.  However, it can range from purely vertical lift to a combined vertical and lateral movement. The yellow region below is generally what we consider “cutter territory”.

With pitching everything is pitcher-specific and relative.  So, let’s look at another prominent cutter-baller, Kenley Jansen.  He doesn’t throw many sliders, but his relative movement can be insightful in understanding what could qualify as a cutter vs. a slider.  Here is his movement pattern for his slider and cutter (source: Brooksbaseball.net, catcher view):

As you can see his slider and cutter both break glove-side, with the cutter having a larger vertical rise than the slider.  In his case, the slider actually breaks downwards.  The following is a summary of what we’d like to see and not see.

What we like to see:

    • Spin efficiency north of 35-40% or higher, especially if the pitcher already has a slider
    • Spin axis in the 10:30 – 12:00 o’clock range
    • Velocity drop vs. 4-seam of about 3-6 mph
    • A greater VERTICAL break than HORIZONTAL
    • Glove-side lateral movement
    • Sufficient horizontal separation from both FBs by at least several inches if not more
    • Relatively consistent spin axis from pitch-to-pitch
    • Consistent spin efficiency

What we don’t like to see:

    • Spin efficiency lower than 35% (as it begins to approach a slider)
    • No glove-side break
    • Somewhat inconsistent spin-axis from pitch-to-pitch
    • Somewhat inconsistent spin-efficiency from pitch-to-pitch (the more inconsistent the spin-axis and spin-efficiency, the more inconsistent the break. This in turn implies less overall command of the pitch)

The cut-fastball grip is similar to a 2-seam fastball grip, with the fingers closer together or touching.  But in this case the fingers are on the outside-inside of the ball at the point of release.  Instead of trying to throw straight through the ball, you throw through the side of the baseball, creating a cut that generates more lift than a slider but not quite as much as a fastball.  The finger placement should create a glove-side type of movement from the point of release.  This means that the ball doesn’t totally spin backwards like a four-seam fastball; rather, it spins backwards with some glove-side lateral spin.

Below are examples of a single cutter and an overall cutter movement pattern.  The most relevant metrics that identify this specific movement as a cutter are as follows:

    • Spin Axis: 11:00 o’clock (similar to Rivera’s above)
    • Spin Efficiency: 49%
    • Vertical Break: 9.5 in.
    • Horizontal Break: -5.5 in.

Here is the video of the pitch above demonstrating release off the hand:

(Aviles Cutter)

When thrown from a right-handed pitcher to a left-handed hitter, or a lefty pitcher to a righty hitter, a well thrown cutter with glove-side movement will quickly move in toward a hitter’s hands.  Just in case you are wondering how to get glove-side lateral movement on a pitch? Here is a list that frankly doesn’t do it justice, but nonetheless attempts to review what would be involved:

    • Slight grip change with appropriate finger placement
    • Adjustment in the final release of the ball
    • Applying appropriate spin axis closer to 10:30 – 12:00 by pulling down on the outside of the ball in that direction
    • Less gyrospin and more vertical and sidespin (higher Spin Efficiency)
    • Trial and error with Rapsodo and high-speed video feedback

With sliders and cutters, it’s really easy to fall into the trap and simply look at video and reach conclusions about the type of pitch.  However, when the ball is spinning in 3 different directions at one time and a lot of the movement is along the y-axis, it can be difficult to observe the spin along the other x- and z-axes.  In just about all circumstances, the combination of the visual and the data are the best way to assess the validity of any pitch.

In closing, if you look at the movement pattern of a cutter closely enough, you’d quickly realize that it kind of resembles a 4-seam pattern from a lefty but thrown by a righty.  Wait! Did we just say a righty throwing a lefty pitch.  Yes, we did, kind of!  Perhaps that’s why when thrown correctly it’s so successful.

For additional articles on pitch design and development on a pitch-by-pitch basis click here.