Bat compression test results describe the amount of pressure required to compress the barrel of a bat. A higher compression result (usually stated in terms of pounds per area) means a barrel’s walls are more rigid. A bat with a lower compression means the barrel walls are more flexible or elastic.
Some believe that a more elastic barrel wall is able to produce faster exit speeds. In large measure, according to every manufacturer and bat engineer we spoke to, the belief is not true. We discussed the topic with every major manufacturer and compile their sentiment, as we understood it, below.
Baseball and Softball Bat Compression
Bat compression can be a useful tool to estimate the performance of a given bat construction, but taking the compression value without reference will almost never provide an accurate measure of true bat performance.
~Kyle Hodge, Product Engineer, Axe Bats
Historically, accurate compression testing has been a slightly useful indicator of ball exit speeds. But, non-linear designs, common in performance bats these days, makes compression tests less useful in predicting exit speeds. As well, quick and accessible compression measurements, made possible by field level compressors, lack precision required to make honest correlations to ball exit speeds.
Measuring only how loose the springs are in your trampoline tells you virtually nothing about how high you can jump.
~Brian Duryea, Bat Digest
We asked several industry experts from major manufacturer to comment on the usefulness of bat compression. Read below what they had to say about bat compression tests predictive power of ball exit speeds.
Bat Compression Test Results
Comparing BBCOR, USA and USSSA Compression Test Results
The Trampoline Thought Experiment
One useful way to visualize how easier compression is not always better is to consider the trampoline in your backyard.
As the springs become more loose on the trampoline, can you jump higher or lower?
The answer, of course, depends. Specifically, how much does the person jumping weigh and how much elasticity is retained in the springs as they become loose? We could imagine an equation that optimizes the trampoline’s effectiveness. That equation, based on factors like the jumper’s weight and leg strength, as well as the quality of the spring’s recoil, would set the optimal amount of taut in the tramp’s springs.
Much like the perfectly dialed in trampoline, a bat’s effectiveness is not always maximized by simply making the barrel walls more flexible. Or, as we might say, loosening the springs of the bat. Instead, the right elasticity in the barrel simply depends. Factors like pitch speed, bat and ball weight as well as the quality of the barrel’s material all play significant factors in the optimal compression. That optimal compression is one factor in ball exit speeds, but far from one and the same.
Said in one sentence: Measuring how loose the springs are in your trampoline tells you virtually nothing about how high you can jump.
When measuring within the same class of bat (BBCOR, USSSA, USA), our bat compression test results provided little predictive power for exit speed.
Measuring the Life of a Single Bat
One general theme we gathered from the experts was that bat compression test results are useful in monitoring the life of a bat. As a composite bat is worked in more, its compression will become easier.
We also had a good back and forth with some engineers at DeMarini who felt, without putting words in their mouth, much like everyone else we spoke to. They add how bat compression done at a field level (with devices like the one you see in the video above) aren’t terribly reliable. Most bats in a particular classification sit real close to each other on a compression test scale. Small changes from one bat to another are not predictive enough, nor is the device accurate enough, to make determinations about ball exit speeds.
Compression doesn’t matter to me, I’m hitting bombs either way…Hitters should focus less on barrel compression and more on swing mechanics, timing and approach at the plate. Blaming your bat for a bad AB is counter-productive.
~Former Oregon Duck, Hailey Decker
Here are some notes we took from our conversation. Paraphrased, as far as we understood it.
- Lower compression does not necessarily mean better performance. Especially when you consider tee work, soft toss and game speeds.
- Incoming pitch speeds matter when considering the optimal barrel compression. And it isn’t always the lowest.
- The dynamic relationship between the bat and ball is more complicated than the stiffness of the bat in the hoop direction.
- Compression is measured, but not used for performance testing certification for a reason.
- Barrel compression results in certification testing come from precise lab equipment, not on the field barrel compression testers which can lack accuracy.
Bat Compression Testing: Industry Experts Take
A well respected Easton engineer had similar things to say. Simply, the difference between compression and exit speeds are uncorrelated enough to put little stock into compression tests alone.
“In the current landscape of many associations/leagues, there seems to be a misconception that bat compression is the end-all, be-all of performance. Compression is the easiest / outer-most layer than can easily be peeled back, but there are many different factors beneath that compression figure that impact the performance of the bat…”
Henry Fitzpatric, Bat Engineer
Those factors include, among other things, both the quality and durability of the material.
Rawlings said, without surprise at this point, very similar things. Compression made more sense as a stand alone performance test a long time ago. Now, construction is “non-linear.” Meaning, bats aren’t simply designed with a single set of characteristics throughout the barrel. As such, measuring pressures at a point of the bat and calling it a performance comparison is not accurate.
When do Compression Numbers Matter?
Compression numbers matter in a few specific instances.
- Some leagues (mostly in the softball space) require your bat be above a certain compression. These compression tests, done at the field level, attempt to remove bats from play that are too hot. Although leagues are obviously more than welcome to enforce a minimum compression test standard for bats in their game, it is far from a test on performance. Several bats removed from play due to a pressure measurement have passed the standards test.
- If you are looking to buy an illegal/doctored bat that has been shaved or rolled, then a compression test pre and post-procedure should tell you the bat has indeed been manipulated. Compression tests are common place for those that sell illegal bats.
- Bat compression test results can tell you how well your bat has been worked in. Our intent at Bat Digest is to provide parents and players a compression number and how many times it takes to work in bats for a better compression. You’ll find that data on our raw exit speed page.