A Review of Blast Motion and Its Swing Metrics

By Bahram Shirazi (RPP Co-owner, MBA, BSEE)

If you don’t own a Blast Motion sensor you should.  We’ve been using Blast sensors for a couple of months now and we are very impressed.  Frankly they are very easy to use and they don’t require calibration prior to hitting.  The only shortfall we discovered early on was how all the metrics related to each other, which actually prompted this internal write-up.

Note: Much of the information here is directly from Blast Motion materials.

Blast reports 3 Swing Quality scores.  Their scores (20-80) are based on relative measurements of similar age groups and skill levels:

    1. [Swing] Plane
    2. Connection
    3. Rotation

The sensor also reports 10 pre-contact Swing Metric scores:

    1. Attack Angle (degrees)
    2. Early Connection (degrees)
    3. Connection at Impact (degrees)
    4. Time to Contact (seconds)
    5. On Plane Efficiency %
    6. Vertical Bat Angle (degrees)
    7. Power (kW)
    8. Rotational Acceleration (g)
    9. Bat Speed (mph)
    10. Peak Hand Speed (mph)

The new Blast 5.0 App also provides several post-contact data points which are not included in this write-up.

Swing Quality Scores

A. [Swing] Plane – Measures the degree to which your swing is on the swing plane and it uses On Plane Efficiency (defines further below) as the primary indicator for your score.   The Score is on a scale of 20-80.  The higher the score the better.  According to Blast, the Plane Score is important for the following reasons:

      • Players that stay longer on plane consistently barrel up balls.
      • Players that stay longer on plane can better adjust with their body.
      • Players that stay longer on plane are more consistent with exit velocity and launch angles.

B. Connection – Links together what your body and your bat are doing prior to and at the point of contact. Maintaining good connection (90 degrees) for all pitch locations is an indicator of dynamic adjustability.  It uses Early Connection and Connection at Impact metrics (both defined further below) as the basis for your score.  The Score is on a scale of 20-80.  The higher the score the better.  According to Blast, the Connection Score is important for the following reasons:

      • Players with good connection display better swing adjustability in all pitch locations.
      • Players with good connection have better plate coverage.
      • Players with good connection generate more power to all parts of the field.

Players who are connected early have a better chance of being connected at impact.  And good Connection generally means you’re using your body to adjust throughout the zone, while maintaining your Rotational Acceleration and On-Plane Efficiency (reviewed below).

C. Rotation – Measures how quickly your bat accelerates into the swing plane. It uses Rotational Acceleration (defined below) as the basis for your score.

Rotation is a good indicator of how you build bat speed by sequencing properly. The quicker your rotational acceleration, the more power you will have and the more time you will have to adjust to pitch locations.  The Score is on a scale of 20-80.  The higher the score the better.  According to Blast, the Rotation Score is important for the following reasons:

      • Players with good rotation display the ability to sequence correctly by using their hips followed by their hands.
      • Players with good rotation display the ability to adjust their swing and better check swing on pitches.
      • Players with bad rotation use their hands earlier in the swing which causes less dynamic adjust-ability.

The quicker you rotate and use rotation to your advantage to build bat speed, the better you are as your level of play advances.  Once again according to Blast, at the Major League levels, the players with the highest Rotational Acceleration have the highest exit velocities and they hit those exit velocities more consistently.

Swing Metric Scores

On-Plane Efficiency % – Measures the percentage of your swing where the bat is on the swing plane. Your Vertical Bat Angle (VBA) at contact establishes the plane for that specific swing. A high % is a great indicator of making consistent contact and barreling balls.

Vertical Bat Angle – Vertical Bat Angle is the angle of the bat (front view) with respect to horizontal at the moment of impact. Vertical Bat Angle is measured in degrees and provides the location of the barrel of the bat relative to the knob of the bat at impact. Vertical Bat Angle will be zero when the barrel of the bat and the knob are parallel to the ground. It will be negative when the barrel of the bat is below the knob of the bat at impact.

What should Vertical Bat Angle be? The Vertical Bat Angle in batting practice or games will mostly depend on the location of the pitch. Steeper angles are required for low and inside pitches, while shallower angles are required for high and outside pitches. Younger players tend to have a slightly flatter Vertical Bat Angle primarily due to strength considerations and swing style. Extreme pitch locations, such as low and inside or high and outside, can result in Vertical Bat Angles beyond the typical dynamic ranges listed below.

I should also note that we have observed excessive VBA due to an excessive initial Torso Bend (from K-Motion tests) in the initial phase of the swing.  This can be related to other issues, such as T-spine / Back problems (more on this another time).

Analysis from Blast database provides typical Vertical Bat Angle ranges for the following age groups and skill levels for baseball:

      • Professional: -25 to -35 deg
      • Minor League MiLB: -24 to -34 deg
      • College: -23 to -33 deg
      • High School Varsity: -21 to -31 deg
      • High School Junior Varsity: -20 to -30 deg
      • Middle School: -17 to -27 deg
      • Youth: -15 to -25 deg

Power– The average Power generated during the swing is found from the effective mass of the bat, the Bat Speed at impact, and the average acceleration during the downswing. Power is measured in kilowatts (kW). Higher Power is achieved when a hitter can swing a heavier bat and accelerate it to higher speeds.

      • Professional MLB: 3.8 – 5.7 kW
      • Minor League MiLB: 3.8 – 5.2 kW
      • College: 3.8 – 5.1 kW
      • High School Varsity: 2.8 – 4.1 kW
      • High School Junior Varsity: 1.8 – 3.8 kW
      • Middle School: 1.4 – 3.2 kW
      • Youth: 0.9 – 2.5 kW

Attack Angle – AA is the angle of the bat’s path (side view), at impact, relative to horizontal. A positive value indicates swinging up, and a negative value indicates swinging down, where zero is perfectly level.

What should Attack Angle be? The average fastball crosses the plate at a 6-degree downward angle, while a breaking ball crosses the plate at a minimum 10-degree downward angle. Other factors could include bat speed and style, pitch velocity and location, and game situation. According to Blast, MLB hitting coaches often teach that in order to hit a line drive, the hitter needs an Attack Angle between 6 – 14 degrees.  Our own internal research confirms a similar range.

Analysis from Blast database provides typical Attack Angle ranges for the following age groups and skill levels for baseball:

      • Professional: 2 to 16 deg
      • Minor League MiLB: 1 to 15 deg
      • College: 0 to 14 deg
      • High School Varsity: 0 to 14 deg
      • High School Junior Varsity: 0 to 14 deg
      • Middle School: 0 to 14 deg
      • Youth: 0 to 14 deg

As I mentioned earlier, our internal research points to an optimal AA north of 5 degrees.  We don’t consider 0 to be optimal.

Early Connection – Early Connection measures the relationship between your body tilt and vertical bat angle at the start of your swing. Establishing good connection (90 degrees) early in the swing helps you get on plane and increases your ability to adjust to all pitch locations.

Connection at Impact – Connection at impact measures the relationship between your body tilt and vertical bat angle at impact. Maintaining good connection (90 degrees) for all pitch locations is an indicator of dynamic adjustability.

Time to Contact – This metric represents the elapsed time between start of downswing and impact. The start of downswing uses an advanced algorithm to detect only when functional forward Bat Speed is initiated.

      • Professional: 0.13 – 0.17 seconds
      • Minor League MiLB: 0.13 – 0.17 seconds
      • College: 0.14 – 0.18 seconds
      • High School Varsity: 0.14 – 0.18 seconds
      • High School Junior Varsity: 0.15 – 0.20 seconds
      • Middle School: 0.16 – 0.21 seconds
      • Youth: 0.17 – 0.23 seconds

Bat Speed – is the observed speed of the sweet spot of the bat at impact. The sweet spot of the bat is measured six inches from the tip of the bat.

      • Professional MLB: 66 – 78 mph
      • Minor League MiLB: 63 – 75 mph
      • College: 61 – 73 mph
      • High School Varsity: 57 – 71 mph
      • High School Junior Varsity: 53 – 67 mph
      • Middle School: 46 – 62 mph
      • Youth: 40 – 56 mph

Rotational Acceleration– Rotational Acceleration measures how quickly your bat accelerates into the swing plane. Rotational Acceleration is a good indicator of how you build bat speed by sequencing properly vs. pulling the bat with your hands. The quicker your rotational acceleration, the more power you will have at contact and you will also have more time to make a decision at the plate.  It is measured during when the bat transitions from the load into the rotation, early in the swing to capture movement patterns of the player.

Rotational Acceleration is hardly ever evaluated in normal settings, yet it could be one of the most important factors in making you successful at the plate.  For example, if your Time to Contact and Attack Angles are lower than they should be at contact, then it could simply be the fact that you just can’t get there fast enough by the time you make a decision to swing the bat.  What’s likely lacking? Your Rotational Acceleration!  I can guarantee you that MLB players have exceptional rotational acceleration numbers.

Peak Hand Speed– Peak Hand Speed is the observed maximum speed as measured on the handle of the bat (measured six inches from the knob of the bat). Peak Hand Speed will occur prior to the moment of impact, very close to the commit time in the swing when the wrists unhinge.

      • Professional MLB: 23 – 29 mph
      • Minor League MiLB: 22 – 28 mph
      • College: 21 – 27 mph
      • High School Varsity: 20 – 26 mph
      • High School Junior Varsity: 19 – 25 mph
      • Middle School: 18 – 24 mph
      • Youth: 17 – 23 mph

Summary

In summary, I think every baseball player should own a Blast sensor.  The information is extremely relevant and useful in training.  So much so that beginning shortly, we will be completely integrating it into all of our training programs, both from an evaluation and training standpoint.  Using it in evaluations will help us identify issues.  While, including them in our training programs on an on-going basis will help improve consistency.

As humans, we never move exactly the same way.  But, next to having the right metrics, reducing variability in the swing should be the number one objective of every player.  Stay tuned as we begin to release our in-house reports on the correlations between Blast, K-Vest (pre-contact) and Rapsodo (post-contact).

Note: All metric ranges by level of play provided by Blast Motion.

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