Using DVS X-Ray to Guide Conversations About Velocity Gains
Every pitcher wants the same thing: reach their potential. And if there’s room to grow, especially in fastball velocity, most athletes will chase it. Our job as coaches, trainers, and development staff is to help pitchers pursue that growth in a way that’s trusted, sustainable, and aligned with long-term health.
That’s where DVS X-Ray creates a major advantage for pitchers.
When we combine a pitcher’s DVS Score with their Arm Impulse metrics, we can frame the conversation from an objective, coachable perspective. Instead of relying on guesswork, “feel,” or generic velocity plans, we can better understand:
How much potential energy and mechanical efficiency does a pitcher create? (DVS Score)
How well is that energy being transferred into ball release? (Arm Impulse)
Arm Impulse metrics have been available inside DVS X-Ray for the last six months. As more athletes and facilities begin incorporating them into each DVS Score analysis, it’s important to understand the context—because the same velocity can be produced through very different movement patterns, workloads, and risk profiles.
Below is a quick recap of the primary Arm Impulse metrics referenced in this article, followed by a coaching-style interpretation of three left-handed USPBL pitchers—each currently throwing 90 mph, each pursuing the next step toward an MLB opportunity.
The Key Arm Impulse Metrics
1) Arm Impulse
Arm Impulse calculates the change in wrist velocity multiplied by the duration of the acceleration window. It helps reveal how efficiently a pitcher builds and carries acceleration into release.
Higher values often indicate a smoother, longer acceleration path and more sustainable energy transfer
Lower values can reflect a short, abrupt burst of speed that may increase stress on the arm
2) Acceleration Smoothness
Acceleration Smoothness measures how consistently the arm accelerates through the final acceleration phase. The blue line represents the pitcher’s actual acceleration path, while the red dashed line represents a perfectly steady increase.
The closer those lines align, the smoother (and typically more efficient) the sequencing
Values closer to 1 are ideal
3) Stretch Angle
Stretch Angle helps describe the relationship between the throwing arm and the upper body’s mass once the arm reaches its vertical apex.
Lower stretch angles often indicate the upper body mass is better “delayed,” allowing the arm and torso to accelerate together
This can support a longer acceleration window and improved Arm Impulse
The Stretch Angle is measured when the throwing forearm reaches the vertical apex. Stretch Angles are highlighted in yellow.
4) Bow Effect
Bow Effect varies from pitcher to pitcher. In this model, it’s measured at the point where the throwing wrist reaches max external rotation.
It’s closely tied to arm timing at foot strike and natural shoulder function
Larger bow effect values can support longer, smoother acceleration—and in some cases, higher Arm Impulse
Many factors early in the delivery directly influence the Bow Effect of a pitcher. If the sequencing of the delivery is efficient leading into this position, a pitcher’s effect will increase, which helps the upper mass and arm work together consistently.
Why This Matters: Leverage Beats Effort
The biggest takeaway is simple:
Improving efficiency and timing into foot strike helps a pitcher transfer energy from better leverage and strength.
That’s physics. When leverage improves, more energy can be converted into speed without relying on sheer force. And when pitchers rely less on force, they generally have a better chance to sustain both velocity and health over time. For example, a longer wrench beats a stronger hand—better leverage creates more torque with less strain. That’s why improving the timing of foot strike can raise velocity while reducing the need for late arm effort.
Three 90 MPH Left-Handed Pitchers: Three Different Development Strategies
For this analysis, we’ll look at three left-handed pitchers from last season in the USPBL: Pitcher A, Pitcher B, and Pitcher C. All three are throwing 90 mph today. All three want to increase velocity and perform at a high level to earn an MLB contract.
But their pathways and the coaching strategy should not be the same.
Pitcher A: “Slow Down to Speed Up”
DVS Score: 11
A DVS Score of 11 signals higher risk and lower delivery efficiency. Even without diving into the full score breakdown, this is a clear indicator that we need to proceed carefully before increasing workload or performance demands.
Coaching Perspective
If we immediately prescribe a velocity-focused program, especially one centered on more strength and power, we may do more harm than good. This pitcher is currently producing arm acceleration from an unsupported position, and his metrics suggest the arm is being forced to “catch up” late.
What the Metrics Are Telling Us
Stretch Angle: 49° → Higher angle = less leverage to accelerate the throwing arm
Bow Effect: 24° → below average, indicates the body is less supportive of the arm during acceleration
Arm Impulse is very low (0.81) → the acceleration window is short and abrupt
Acceleration Smoothness is extremely poor (-0.18) → the arm path “meanders” before final acceleration
The arm is late at foot strike (not parallel to the spine), forcing the forearm to travel extra distance before it can even enter the layback-to-release window
In real terms, this is the type of athlete who can often “compete” at 90 mph, but the delivery is asking the arm to solve the problem late—more stress, less support, less margin for error.
Pitcher A as he moves into Foot Strike - The Gateway Position
Pitcher A’s Acceleration Smoothness Curve
Recommended Strategy
Role: Low-inning reliever until measurable progress is made
Primary goal: Improve timing and leverage before chasing velocity
The first step is to help him accelerate from a stronger position—getting the arm more on-time at foot strike and training a longer, more efficient acceleration path. As the DVS Score improves, we monitor shoulder function, strength, recovery patterns, and workload tolerance.
Bottom line: Pitcher A needs time and benchmarks before high-level velocity conversations make sense.
Pitcher B: “Big Potential, Needs Structure”
DVS Score: 14
Pitcher B shows a stronger DVS foundation than Pitcher A, and importantly, he shows the ability to accelerate deeper into the throw.
What the Metrics Are Telling Us
Arm Impulse is high (1.6) → strong capacity to build and carry acceleration
Acceleration Smoothness is low (0.29) → the acceleration isn’t clean yet
Arm timing at foot strike is still very late, which keeps the risk elevated until corrected
This is a pitcher who likely has real velocity upside, but the delivery still has inefficiencies that can leak energy and increase stress.
A Key Reminder!
Across large samples, we often see that for every 1-point improvement in DVS Score, average fastball velocity improves by ~0.4 mph (on average). That doesn’t mean every pitcher follows the same curve—but it’s a meaningful directional framework when paired with Arm Impulse and workload strategy.
Pitcher B as he moves into Foot Strike - The Gateway Position
Pitcher B Acceleration Smoothness Curve
Recommended Strategy
Role: Low-inning reliever → progress toward long-inning relief as benchmarks improve
Primary goal: Clean up timing and sequencing early in his delivery to help him become on time at foot strike and use his natural skill set to accelerate from a position of greater leverage.
As his DVS Score improves—especially by getting the arm more on-time at foot strike—he should naturally reduce stretch angle, maintain (or improve) his strong Arm Impulse, and begin using body mass and leverage more effectively. That’s where velocity can become safer and more repeatable, rather than just harder.
With positive changes in shoulder range of motion and recovery patterns, Pitcher B could potentially build toward a starter’s workload—an important step in increasing value and prospect status.
Pitcher C: “Green Light Foundation”
DVS Score: 16
Of the three, Pitcher C shows the best overall combination of movement quality and transfer metrics.
What the Metrics Are Telling Us
DVS Score indicates he’s close to on-time at foot strike
Stretch Angle: 43° → supports better mass positioning
Bow Effect: 37° → helps lengthen and organize acceleration
Acceleration Smoothness: 0.90 → very efficient sequencing
Arm Impulse: 1.49 → strong transfer into release
This pitcher is showing a pattern that typically supports performance gains without immediately compounding risk—assuming health, mobility, and recovery benchmarks are in a good place.
Pitcher C as he moves into Foot Strike - The Gateway Position
Pitcher C Acceleration Smoothness Curve
Recommended Strategy
Role: More flexible (starter development becomes realistic)
Primary goal: Gradually build a bigger energy system and workload capacity
This is the type of pitcher who often benefits most from structured development because the foundation can support it. With Pitcher C, we can confidently begin conversations about increasing workload and scaling performance demands—because the delivery is already doing a better job of organizing the transfer of energy.
Conclusion: Objective Clarity Creates Better Development Decisions
At the end of the day, DVS X-Ray gives pitchers clarity, and it gives coaches a more objective roadmap for how to develop the athlete in front of them. But the metrics only matter when they’re framed correctly.
A pitcher’s career stage, health status, recovery profile, and current role must be part of the interpretation. Sometimes, the most effective pitcher on the field today might be the athlete who needs the most careful long-term strategy. Pitcher A may help a team win right now but the responsible decision is to protect his future while building the foundation that allows him to sustain higher demands later.
When we combine the DVS Score (how energy is created) with Arm Impulse (how energy is transferred), we can make smarter decisions about training, workload, and velocity development—without turning every pitcher into the same template.
Want to Integrate DVS X-Ray Into Your Program?
If you’re interested in bringing DVS X-Ray into your pitching program and using DVS Score + Arm Impulse to guide development decisions, reach out anytime:
justin@dvsbaseball.com
