How Brewers GM views new bat tracking data

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Brewers general manager Matt Arnold never met a metric he wasn’t at least willing to consider, and the recent release of Statcast's bat-tracking data has him thinking back to his earliest days in scout school.

“It’s a box you would check on the scouting report,” Arnold said. “But the distinction is there’s a big difference between bat speed and hitting. You just have to be careful with that with hitters.”

Thankfully, there’s a lot more to the new data than bat speed, though that may be the simplest to understand for any baseball fan. We knew that Brewers catcher William Contreras had a quick bat. Now, we can measure how quick, and how Contreras stacks up against teammates and the rest of Major League players in that and a number of other categories. The data also could prove helpful if changes occur as the season wears on.

If this is all news to you, MLB.com’s Mike Petriello expertly explained what it means and why it matters in this story. You can see and sift through the data yourself on Baseball Savant.

Here’s what you’ll find:

Bat speed: Just as velocity isn’t the only measure of a good pitcher, bat speed is not the only measure of a good hitter. But anyone who enjoyed watching Paul Molitor knows that it can play a big part.

Fast-swing rate: A player’s “fast-swing rate” is simply showing the percentage of all of his swings at or above 75 mph. Why that figure? Similarly to how a hard-hit ball is one with 95 mph and up of exit velocity because that’s where it begins to “matter,” 75 mph of swing speed is where you see per-swing production reach MLB average, with gains then accruing as swing speed increases (to a point).

So it’s a stat that matters differently from player to player. Brice Turang’s fast-swing rate is just 4.3 percent, and he’s been one of Milwaukee’s most productive hitters this season. Contreras leads current Brewers at 48.8 percent.

Swing length: A long swing typically generates more power with more swing-and-miss. Shorter swings are more direct, creating more contact with less impact. It all depends on the player, the opposing pitcher, the situation and myriad other factors from health to the weather. The point is we now have a measure.

Willy Adames has the Brewers’ longest swing, averaging 8.1 feet on so-called “competitive swings.” And Turang has the shortest by quite a margin, at 6.0 feet.

Squared-up rate: There’s some physics involved here, but It boils down to how often hitters make contact on the sweet spot of the bat. It doesn’t always take a fast swing, either. Blake Perkins’ fast-swing rate is just 3.3 percent, but he leads MLB in squared-up rate, at 48 percent, just ahead of runner-up Luis Arraez and then Juan Soto and Contreras. Quite the company.

Blasts: Put simply, a blasted swing is squared up and fast. Squaring up a ball is good, and doing so with elite bat speed is even better. Here’s where Contreras really shines, so much that it inspired Petriello to write a whole article about it.

If it wasn’t clear from the above descriptions, there is a lot to digest here. Ted Williams wrote a book called “The Science of Hitting,” but no one ever said it’s an exact science.

And that was Arnold’s message as he discussed the new data.

“Back in the day, it was just looking at how guys swung and figuring out mechanically how they got to bat speed,” Arnold said. “Now that you can measure it, it’s pretty cool.

“But there are different profiles that get to value in different ways. [Luis] Arraez doesn’t test off the chart on specific metrics, but he’s a great hitter.”

Arnold’s message: Embrace the nuance.

“When you just rely on one stat or one measurement, you’re missing the whole body of work,” he said. “You can fall in love with one ingredient, but it doesn’t tell the whole story. That’s the hard part of all of this.”