Pitchers Who Pitch to Their VAA

When something becomes sexy, I’m all in. Crocs and socks? Sexy. Minivans with a built-in vacuum cleaner to suck up all the floor Cheerios? Sexy. Throwing a four-seam fastball with a very shallow vertical approach angle due to some serious induced vertical break at the top of the zone? Sexy. Some things some people just can’t pull off. But when a trend becomes a trend, you’re either in or you’re out.

Measuring the shape of a fastball with multiple data points and summarizing that into a score is an overly simplified way of explaining how Stuff+ and PLV work. Alex Chamberlain does great work with his pitch leaderboard making metrics like vertical approach angle (VAA) and horizontal approach angle (HAA) available to analysts, baseball nerds, and baseball couch potatoes alike. After seeing Alex’s presentation at PitchCon2o24, I was interested to know on a large scale which pitchers are pitching as their VAA plays best. If you’ve never heard of VAA before, you should start with Chamberlain’s primer article, jump to Simple Sabermetrics’ video overview, and then, if you’re looking for a pallet cleanser, head on back to this article.

You can also just choose to stay here noting that VAA is simply the angle at which a pitch enters the zone measured below the flat, horizontal line that extends from the mound to the plate. Gravity will force all pitches to enter with a negative angle, but some pitchers can make their fastballs flatter, or less negative, than others. Spencer Strider is the poster child for throwing a flat fastball and like Chamberlain’s research points out:

we celebrate flat four-seamers up (with gutsy, elite four-seamers down the middle), steep sinkers down, all kinds of breaking and off-speed pitches down, and a hanging secondary in favor of a hanging fastball.

I want to know who did that (^) in 2023. Or, more specifically, this:

1. threw a four-seamer at the top of the zone (Statcast zones 1, 2, and 3) more than 20% of the time.
2. had a vertical approach angle above average (VAA AA) or greater than 0.
3. threw a four-seamer with an average velocity greater than or equal to 94 MPH.
4. threw more than 1,000 four-seamers in 2023.

That’s all to explain a fast, flat fastball up in the zone often. Whew! Still with me? Who has demonstrated the above with regularity?

Let’s take it a step further and look for the pitchers from the list above who also throw a significant portion of their breaking pitches, in this case, sliders, curveballs, and sweepers, low in the zone (Statcast zones 7, 8, 9, 13, and 14). I’ll also bring in overall Stuff+ metrics to add a little color:

Grayson Rodriguez, Dean Kremer, George Kirby, Bryce Miller, Ryne Nelson, Ken Waldichuk, and Michael Kopech fall off as they aren’t locating their breaking balls low in the zone often enough. Let’s take a look at George Kirby’s heat map to see why he falls off:

I’d venture to say that Kirby is locating his slider very well against righties, but could benefit from lowering the pitch slightly to lefties. Here’s a comparison of how the pitch performed against batter handedness:

VS Righties

• BA: .246 xBA: .248
• SLG: .333 xSLG: .360

VS Lefties

• BA: .306 xBA: .321
• SLG: .472 xSLG: .390

I’m not smart enough to make recommendations to major league pitchers, but I did stay at a Holiday Inn last night and George Kirby might benefit from throwing the slider less often to lefties.

Instead of looking at the pitchers who throw high and low with effectiveness, let’s just look at the pitchers who throw steep sinkers low in the zone. Ben Clemens detailed the Giant’s usage of sinkers low in the zone and their ability to garner called strikes. It’s a great read. Pitchers who have taken to this new trend seem to have something going for them. Who sat at the cool kid’s table in 2023?

Oddly enough, no pitchers are sitting in both sections of the cafeteria. Four-seam cool kids and sinker cool kids are forming separate gangs. From a fantasy perspective, it’s nice to see who is practicing the skills that have been proven successful. There are a few names in these tables that might spark a little more digging. Some can likely be ignored. But I certainly remember going through a bit of a persona change in middle school when I finally ditched my crummy winter coat for a pull-0ver Starter jacket and became, finally, cool. For about a week, at least.

What’s in is in, no matter how you feel about it. It’s 2024! People are wearing headphones with wires again, sneakers just keep getting stranger, and soon we’ll all be walking around with computers that look like snow goggles shielding our faces. What will happen to fastballs? Sinkers? Breaking balls? We’ll just have to wait and see.