It’s Time for a Pitcher to Throw 80% Breaking Balls

A few years back, I was sure that throwing too many breaking balls was bad for pitchers’ arm health. I wasn’t alone — there was some decent research backing up that hypothesis. As the methods for examining the question have become more refined, however, and further work has been conducted on the matter, it looks like we’ve found that it’s not so much breaking balls as velocity that most directly affects arm health.

Perhaps teams have been on the same journey, because curveball usage — and breaking-ball usage, in general — is up to heights we haven’t seen before.

Breaking-ball usage has increased. That said, the uptick has been slow and gradual. Perhaps too slow and gradual. Maybe we should be pushing it.

We’ve written a lot about the juiced-ball theory, but when Ben Lindbergh recently published results from Major League Baseball’s internal ball testing — which produced no indication that the ball would be responsible for the marked increase in home runs — we were left scratching our head as to what the actual cause might be. Russell Carleton over at Baseball Prospectus thought that we could explain a good deal of that increase with a simple look at hitters’ tendencies. Take a look at what he found:

Starting in 2015, around the time of the current power spike, hitters seemed to be sitting fastball more. And why not? Even though fastball usage has actually declined among pitchers, it still accounts for more than half of all pitches. As a batter, you know you’re eventually going to get one. So, why not wait for one and swing really hard? You might miss and eventually you might strike out, but if you do, so what?

Within that piece, there’s evidence that batters are swinging less often and have pushed their average pitches per plate appearance close to four (3.8 last year), up from 3.5 earlier this century. What Carleton proposes is that hitters, now armed with the terminology and technology to discuss and improve how hard they hit the ball in the air, are sitting on fastballs because they’ll still get, on average, one or two per plate appearance.

What if they didn’t, though? We’re talking about a potentially healthier approach for a pitcher — fewer high-velocity fastballs — and also pushing the expected number of fastballs per average plate appearance under one. Can batters use the same approach if they might only see one fastball a night? Or two? The evidence is that velocity differential is not as important for whiffs on breaking balls — it’s not quite like a changeup in that regard, the breaking ball may not need the fastball as much as a changeup does.

What if a pitcher started throwing 80% breaking balls?

One possible outcome might be that said pitcher would walk a lot of people. And that’s a decent hypothesis. Here’s how those big groups of pitches from above rank in terms of zone percentage according to a piece by Harry Pavlidis from back the day. (Note: cutters have been removed from the breaking-ball group in this case.)

The average breaking pitch doesn’t land in the zone as much as the average fastball, no. But if you had a pitcher with multiple distinct breaking balls — and good command of those pitches — you might want to consider pushing that breaking-ball percentage as high as it can go, right? Here are a few pitchers who throw a ton of breaking balls already and also feature good edge percentages on those breaking balls. They could be our best test cases.

Given his success, Clayton Kershaw probably doesn’t need to change anything up, despite his excellent command of his breaking balls. But Yovani Gallardo? Bronson Arroyo? Kenta Maeda? Ricky Nolasco? Jordan Zimmermann? Over the last few weeks, you could add Adam Wainwright and Josh Tomlin, and that would make sense. There’s enough struggle in their recent histories and enough upside in this idea that they might be inclined to go for it. They’ve each got multiple breaking balls and above-average command of those breaking balls — by this incomplete measure at least.

Of course, getting them to agree to be the guinea pigs in our grand experiment won’t be easy either way. Maybe they aren’t so excited. We’ll have to tell them about the whole arm-health and hitters-sitting-dead-red part so they buy in. Maybe if we tell them they’ll be way out in front when the robot umps come — that they’ll be the most ready to take advantage of the new parts of the zone that will open up then — maybe then we’ll get ourselves a pitcher ready to completely flip the script on today’s batters.