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After measuring thousands of exit speeds, we’ve found swing weight as the most important factor in predicted exit speeds. To be sure, swing weight is the most important feature of the bat, but not of the swing. Bat speed, mechanics, and other things that are hitter controlled are more important than the bat. In terms of what the bat can control the swing weight, not barrel performance, is the single most important factor in predicting and improving exit speeds.
A bat size chart is also a good place to start. But, remember, the stated weight of a bat is not the same as its swing weight. Bats with the same scale weight can be upwards of 10% different in feel.
Measuring swing weights is a colossal and expensive task. To measure the bats, we need to own them. It also takes time to find the balance point, scale weight, and pendulum period of the bat. As well, the formula for measuring swing is not uncomplicated.
We share our swing weights with our email subscribers. These include all the swing weights from every year and every league. Once subscribed, you’re given access to a page with all the swing weights and is updated every 60 days or so.
Although we are confident in our swing measurements’ repeatability, we do not submit they are perfect. Our best estimate is we run no less than 200 points off. Meaning, a percentage swing of 2 to 3%, either way, would be a reasonable margin of error.
A percentage point or two one direction or another is virtually indistinguishable to any given player. A bat with a 4% change in any given direction on the above chart is likely not noticeable by anyone.