Sophomore Shortstop Jayden Acevedo (Don Bosco Prep) started training at RPP last summer. In general, he was looking to increase his overall strength and power, increase his exit velo and throwing velocity, and improve his consistency at the plate. By the end of February this year, his top-end velo had improved from 79.9 to 87.2 mph, and his infield throwing velocity had improved from 73 to 84 mph.

How did he do it? Quick answer… a lot of hard work…

High school age position players that are eligible to enroll in our more advanced strength training programs begin the process with a comprehensive physical and mechanical evaluation. This includes the following:

1. Physical Assessment – Covers a number of important topics, including (a) lower and upper half mobility (b) lower and upper half strength (c) lower and upper half power (d) speed – 30-yard dash, (e) lower and upper half elasticity – (f) decel metrics, (g) body fat % and lean mass ratios and finally a force-velocity evaluation profile.
2. Mechanical Assessment – Represents a complete analysis and reporting of the athlete’s hitting mechanics, including, (a) video analysis – linear and rotational phases, (b) Blast Motion metrics, and (c) K-vest Postural analysis.

By the conclusion of the evaluation, we have an excellent idea of strengths and weaknesses that need to be addressed to optimize performance. There is NO better blueprint!

1. Physical Assessment

Body Composition

Below is a summary of Jayden’s height, weight, and body fat % in the beginning of the program.

- Height – 68”
- Weight – 140 lbs.
- Ratio – 2.06x (desired rage of 2.5 – 3.0)
- Body Fat – 11%

Over the course of the off-season, Jayden added 8 lbs. to his frame, improving his height to weight ratio to 2.14x, while maintaining a body fat percentage of 11%. We believe that a big part of his jump in velo is due to him putting on 8lbs. of muscle. More work to go here but things are moving in the right direction.

Upper and Lower Half Mobility

The movement screening portion of the assessment is essential in identifying mobility and / or stability issues that may hinder the athlete’s ability to get into optimal positions throughout the delivery. In most cases, the issues that are presented in this portion of the assessment will be visible when we are evaluating the athlete’s mechanics in the video analysis portion of the assessment.

Jayden’s assessment in June of last year highlighted extremely tight hamstrings- mostly due to inactive glute engagement which forces the hamstrings to do the glutes job of stabilizing his lower half along with the quads and core. He also presented with tight lats as well as low ROM externally on his throwing arm which was inhibiting him to get into adequate layback.

By March of this year, he had substantially improved many of his baseline issues, especially learning to use his glutes which as we can see below, really freed up his hamstring length (ASLR). We also saw him grab a bunch more ext. rotation on his throwing arm.

Note – Jayden presented initially with “overly loose” hips (laxity) so, while we needed to get some length from his hamstrings, we needed to tighten up his hips in order to grab more stability from his lower half.)

Upper and Lower Body Strength

After completion of the movement screen, we move on to our strength and power testing to help give us more information about the type of athlete we were dealing with. Higher gains in these two categories help to create not only a higher ceiling, but an overall more athletic body.

The following is the summary of Jayden’s 1RM metrics in the weight room, in June 2024 and March 2025. Jayden remained consistent in the weight room and as you can see, he has made significant improvements. While these gains are great, as he puts on more lean mass these numbers should go up considerably once again.

- Trap Bar Deadlift – 328 lbs. vs. 416 lbs. >> 26% improvement
- Single Leg Goblet Squat – 68 lbs. vs. 85 lbs. >> 25% improvement
- Bench Press – 143 lbs. vs. 154 lbs. >> 8% improvement

Lower and Upper Half Power

Power is all about how quickly we can produce Force. In baseball, you need to be both strong and powerful. Power = Force X Velocity

Lower Half – With respect to power, the first test we complete is a Counter Movement Jump (CMJ). This jump is performed to assess the athlete’s ability to utilize their Stretch Shortening Cycle and relates to the velocity portion of the power equation and ultimately gives us one half the athletes Force-Velocity profile.

The second test, Squat Jump, is performed to evaluate the athlete’s ability to use muscular force and relates to the force side of the power equation and Force-Velocity Curve.

Jayden’s lower half power has improved significantly as can be seen in the graph below. This means that not only did he get stronger, but he is applying that strength at a faster rate, which is pure gold for baseball players.

Upper Half – We test upper half rotational power on a Proteus Motion machine, utilizing two different tests:

- Trunk Rotation – Similar to the squat jump this involves no “pre-stretch”
- Plyo Trunk Rotation – Same movement with a “pre-stretch”

Once again, Jayden’s gains are apparent below. Better upper half strength and faster application of that strength.

Decel

This test looks at the ability of the athlete’s lead leg to hit the brakes immediately at foot plant and in turn transfer force back up the kinetic chain to use during the throw, or in the case of the test, how quickly they can land on one leg and turn that force the other way with a jump. Jump height and contact time give us what is known as a “Reactive Strength Index” (RSI).

Jayden’s Front Leg RSI metrics are excellent. This implies that his ability to decelerate quickly and turn it back the other way is excellent. However, the amount of power he puts into the ground upon landing (RFD) is compromised, mostly due to his lighter mass and his need to get stronger. Once his ability to put more force into the ground energy transfer up the chain will increase exponentially.

2. Hitting Mechanics

The hitting mechanics evaluation involves three different components:

- Video Analysis
- Blast Motion Swing Metrics
- K-vest Postural Analysis

Video Analysis – Jayden’s hitting mechanics have improved dramatically during this time period. The following is a summary of Jayden’s video analysis before and after, which demonstrates how he has cleaned up much of his initial load and maintaining his center of mass as he begins the linear phase of his swing.

Blast Motion Swing Metrics – The following is a summary of Jayden’s more relevant Blast Motion metrics at the start of this training program last year:

- Early Connections (EC) – 96 degrees (85-100 optimal)
- Connection at Impact (CI) – 84 degrees (85-100 optimal)
- Net Difference btw EC and CI – 12 degrees (<15 degrees)
- Rotational Acceleration – 11 g (11-15 g)
- Bat Speed – 61 mph (53-71 mph)
- Attack Angle – 21 degrees (5-12 degrees)
- Power – 3.0 watts (2.8-4.1 watts)

Three of the above metrics stood out in his initial eval as areas that we needed to address (colored in red):

- Increasing Rotational Acceleration (RA) and Power – By March, on the strength and power side of his swing, Jayden’s RA remained steady at 11g, while his swing power metrics had improved by approximately 10%.
- Reducing the Attack Angle – The significant improvement in his swing metrics came from reducing his Attack Angle from 21 to 11 degrees. This reduction should have a significant impact on his ability to make solid contact. Our suggested range for AA is 5-12 degrees. At 21 degrees (his initial measurement), it becomes increasingly difficult to make solid contact with pitches of higher velocity. Having reduced his average AA to 11 should have a significant impact this spring and summer.

K-vest Postural Analysis – K-vest is a biomechanics tool that allows us to evaluate a player’s kinematic sequence and postural metrics during the swing.

Kinematics sequence is the process by which the athlete creates angular velocity up the kinetic chain, beginning with the pelvis (1), to the torso (2), to the shoulder (3) and finally to the hand (4). The following is a summary of his before and after sequencing metrics. You can see the improvements below in both sequencing and final angular velocity. These improvements should help Jayden become more adjustable at the plate with various pitch locations and speeds.

Postural metrics are the measurements associated with specific body parts at 3 different points along the swing, at heel strike, at first move and at contact. Jayden’s hitting mechanics had very minor postural disconnects as outlined below. The two that we focused on were those that were contributing to his high Attack Angle:

- - - Pelvis Side Bend at Heel Strike
    - Pelvis Side Bend at Contact

Assigned Drill Work

Addressing mechanical disconnects is often addressed by work both in the weight room and specific drill sets we assign the athlete to be performed on a daily basis. The purpose of the drill work is to improve overall movement patterns and sequencing. The following drills were assigned to Jayden during the off-season:

- Activation: Med Ball Decels
- Movement: Feet Together
- Activation: Seated Load (Dry)
- Movement: Step Back Drill
- Movement: Big Papi
- Movement: Top Hand
- Movement: Ty Cobb
- Movement: Scissor Kicks

Over the course of several months, these drills were progressively integrated into Jayden’s training to address mechanical disconnects and improve overall movement patterns. At the start, activation drills like med ball decelerations and seated load were used to build strength and reinforce proper sequencing.

As Jayden became more proficient, more dynamic drills, such as the feet together and step back drills, were incorporated to further enhance movement efficiency and consistency throughout the offseason.

Summary

Jayden has made big strides in his development with much more to come. By the end of February this year, his top-end velo had improved from 79.9 to 87.2 mph, and his infield throwing velocity had improved from 73 to 84 mph. His biggest areas of potential improvement are purely physical. He needs to continue consuming adequate calories while lifting throughout the in-season.

There’s nowhere to go but up for this kid! Keep up the hard work!

Before and after video below…

By Andrew Pezzuto, Nunzio Signore and Bahram Shirazi