How to Improve Unintentional Cut on a Fastball

cut fastball

Improving an unintentional cut on a 4S fastball can be particularly challenging. It’s a habitual release pattern of the ball with a cut and trying to change years and years of a specific movement pattern moving at high speeds requires dedication and work. In this article, we are going to review many of the methods we’ve have used with some success when addressing excessive and inadvertent cut on a fastball.

However, this article does come with a disclaimer: We’re not necessarily suggesting that you must fix a cut on your 4S fastball. If a cut fastball is an effective pitch for you, and you would like to continue to throw your 4S fastball this way, you should continue throwing it that way. This article is meant for those who have a cut and would like to adjust their fastball to move like a regular 4S fastball with additional back spin and perhaps higher velocity.

What does a cut-fastball look like out of the hand?

By cut fastball, we’re not referring to a cutter pitch, which is thrown intentionally as a fastball with a much lower spin efficiency (35-45%) and an intended movement pattern different from a regular fastball.  This pitch is thrown with the intention of a 4S fastball, but as you can see from video the release is slightly off center and the ball has some degree of gyro spin.

(Cut Fastball w/ spin efficiency of 68%)

Cut fastballs generally occur because the athlete’s middle finger is too far on the outside of the ball, causing an increase in gyro degree and causing the index finger to generate a high portion of gyro spin.  Compared to a 4S fastball, the middle and pointer finger are positioned more in the middle of the baseball and leave the ball simultaneously resulting in more pure backpsin.

(Fastball w/ spin efficiency of 96%)

What could be contributing to a unintentional cut-fastball?

Habit – You’ve been throwing it this way your whole life and never really realized it, which is often why it’s a difficult topic to address.

Recent Tommy John Surgery – Many of the pitchers that we see with a cut-fastball are the guys in the gym who are actively recovering from Tommy John Surgery. Reconstructing the UCL generally results in a tightening of the pronator mass in the forearm. The inflammation in the pronator mass may result in the arm not being able to fully pronate and results in the supinated hand release found in most of these pitchers who cut their fastball. Generally, as their throwing programs progress into the ending stages, the inflammation begins to dissipate, and the athlete returns to spinning the ball properly.

Mobility / Strength Issues – Mobility issues such as inefficient ranges of motion (ROM) can also contribute to an inadvertent cut fastball:

    • Hip ER and/or IR
    • Shoulder ER and/or IR
    • T-spine Mobility
    • Insufficient Anterior Core Strength

These mobility issues combined with a lack of strength, especially in the younger athlete with less weight room experience, will make it difficult for pitchers to hold on to, and maintain mechanical torque or tension in the throw.  This can cause a less than optimal throwing pattern and the inability to stay on the ball longer, which brings us to the next topic, pitching mechanics.

Pitching Mechanics – Below are some of the mechanical issues we see often that could also be contributing to an inadvertent cut-fastball:

Poor Horizontal Abduction (scap load) – Performing a good scap load helps resist early trunk rotation while maintaining a good trunk stack into foot plant. It’s also a key player in producing good hip/shoulder separation. We want to see the scap loaded back behind the torso and the arm in a position to enter external rotation more efficiently (see Figure 8 Rocker drill further below).

Early Trunk Rotation – An athlete who is open with his chest before foot plant may be pulling off too aggressively with his chest thus causing his hand to supinate in order to throw the ball towards his intended target (see Marshall’s below).

Slow Angular Velocity of the Hips, High Angular Velocity of the Torso/Arm – An athlete with slow angular velocities in the hips, and higher angular velocities in the torso may result in the athlete aggressively rotating with his torso. This would cause an altered extension and release point which may result in some cut.

Wide Glove Pull – A pitcher who is overly rotational with his glove-side may pull his chest and his throwing arm toward his glove side which may result in a cut fastball (see Marshall’s below).

Hooking the Ball – A pitcher who hooks his wrist in after hand break require more movement to then straighten the wrist into release. If they have poor spin efficiency metrics, most of the time the movement of the wrist does not return to a spot with enough pronation to allow the ball to come out cleanly.

Poor Post-up – A pitcher with a poor post-up will not have efficient stability in their lower half. Instability will then travel up the kinetic chain and may present weaknesses in the athlete’s overall ability to control the rest of their body, specifically their throwing arm, into release (see PVC Post-up drill further below).

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How to improve the inadvertent cut on the fastball?

Addressing a cut-fastball can be a process.  Generally, habitual movement patterns have set in and it will require a good amount of dedication and hard work.  But it is definitely possible.  However, needless to say, there will be process of trial and retrial until you begin to see results from one or some the following alternatives.

The best way to instantly see if adjustments are yielding positive results is to use a pitch tracking software such as Rapsodo or Trackman. Cutting a fastball will be visible during catch play or during bullpens, but using Rapsodo will give you instant feedback on the extent of your cut.  Instant feedback will lead to a quicker ulimate fix.

Drill work – After mobility and strength issues have been addressed, we can further attack any mechanical issues above with drill work.

    • Marshalls into a High Armside Target – By placing the target off-centered towards the pitcher’s arm-side, we are forcing an external cue during the throw and making the athlete pronate more extensively into release.

    • Figure 8 Rocker Drill (Scap load) – The Figure 8 rocker drill helps to kick the arm back into a more pronounced scap load by keeping the movement of the arm constant and using momentum effectively.

    • PVC Post-up Drill (Poor Post Up) – The PVC post up drill is meant to exaggerate the post up by giving an external block that the athlete is not meant to touch. Establishing the post up and improving stability in the front leg will lead to added stability through the rest of the kinetic chain in the delivery.

External Cues During a Bullpen

    • Off Centered Target – Another approach would be to take your target or have your catcher move into the arm-side batter’s box. By moving the intended target to a wider arm-side position, it will force the athlete to decrease the amount of supination in the throw and force more pronation. The pitcher will have to force the palm of his hand to be more direct to a far inside target. Start the bullpen further out and progressively move the target/catcher back to center. We still want the athlete to throw a bullpen to a normal target throughout his pen. Try to repeat the feeling of the beginning throws as the target moves more toward the normal placement.

Catch Play – Let’s go over a few tools and cues that we also use to address a cut fastball.

    • Clean Fuego – The Clean Fuego is a great tool for helping an athlete stay behind the baseball in order to spin the ball straight and to reduce cut.

    • Taped Baseball – You can take some duct tape and wrap a line around the baseball. This tape should be placed in between the fingers wherever the 4-seam fastball grip is held. We usually have our pitchers begin with the Clean Fuego and then move onto a taped or marked baseball, to increase their feel with an actual baseball.

    • Palm to Target – In order to reduce supination during the release, a cue we use frequently with our pitchers is to place their palm towards their intended target. This will increase pronation into the finish and limit the amount of cut on a pitch.
    • The Bernstein Method – The Bernstein method was created by one of our high school pitchers during an attempt to fix his spin efficiency. He tried putting his ring finger next to his middle finger on his fastball grip. For him, having the extra finger on the ball prevented his desire to supinate during release. His spin efficiency metrics went from 60% to a consistent 95%.

You should progress and blend all of these drills from basic catch play to throwing off the mound.

Grip Changes – One simple change you can make is with the grip on your pitches. Bullpen sessions are meant to work and experiment on different aspects of your delivery and your pitches.

    • Wider Grip vs Tight Grip – Change pressures on different fingers. A right-handed pitcher may want to put more pressure on his index finger to work with more pronation.

cut fastball

    • Change-up Feel – If the pitcher has a good changeup, then they are likely excelling with pronation for that pitch. I’ve had success with increasing fastball spin efficiency by simply telling our pitchers to throw their fastball like their changeup. Pronation increases, and the cut on their fastball dissipates.

Last Resort

If all changes have been attempted, the final resort you can go to is asking the pitcher if he would like to throw a cutter in place of his fastball. The pitcher is already placing his hand in a position to throw a cutter, so if we teach him a cutter grip, we may see some positive results with this pitch. This is a change that the pitcher must be completely comfortable with before making this adjustment, as it will completely change the style of pitching that he is used to.


For pitchers who have struggled with adjusting an inadvertant cut on their fastball, beware that it takes commitment and hard work and extended amount of time to correct. The first step is to recognize what part of your delivery may be causing it and then making the necessary adjustments to address the issue. Every pitcher is different, so how you go about fixing this specific issue will likely be different for each athlete.

By Mike Lembo (BS, RPP Pitching Coordinator)

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