Stuff+ has thoughts about the Atlanta Braves

We're going to emulate some of MLB's most successful franchises and scout based on pitching traits

In Moneyball¹, there’s a moment where Athletics general manager Billy Beane is trying to get his scouts to understand that the team can’t afford to replace Jason Giambi…but they can “recreate him, in the aggregate”. It’s Billy’s way of introducing a new way of looking at MLB free agents - as quantifiable bits of production that you can slice, mix, and combine to replace the production of a player who was too expensive for you to retain in free agency.

Suffice to say, MLB has moved on to more advanced measures. I heard an anecdote recently from a baseball operations person about how the best organizations at scouting pitching and arms in the draft aren’t even weighing results that much anymore, they’re looking at pitch characteristics.

(That same person finished the anecdote with a dig at the Rockies, by saying that not only were they looking at results, they were looking at ERA over something more modern and with actual predictive power.)

Let’s do that same thing: Here’s what Stuff+ thinks about Atlanta’s pitching staff entering the season.

What is Stuff+?

(If you’re familiar with Stuff+, feel free to skip ahead to the next section)

Created by Eno Sarris (now with The Athletic) and Max Bay (who just finished some work for the Astros and is now a Sr. Quantitative Analyst for the Los Angeles Dodgers), it’s an attempt to quantify the effectiveness of any given pitch based on how those pitch characteristics have performed in the past.

It’s looking at velocity, obviously, but also release height, horizontal and vertical movement of the pitch, spin rate, arm angle at release, vertical approach angle to the plate, etc. The goal here is to be able to give you a final grade that details how easy or hard it is to hit that pitch versus other pitches of the same type (fastballs, breaking, offspeed) and the other pitches in your arsenal.

To simplify it, it’s an attempt to put a number to how filthy someone’s stuff is, hence the name “Stuff Plus”.

It’s not perfect - no analytical measure is - but it is both pretty predictive and stabilizes quickly, two factors that have led to its rapid adoption. After only 250 pitches, in-season Pitching+ numbers (which is a combination of Stuff+ and locations grading, correspondingly called Location+) outperform preseason predictions for relievers. Starters take about four or five starts, typically 400 pitches, before their Pitching+ numbers reach the same level of outperforming preseason projections, but since they amass many more pitches per start, it’s a similar amount of time into the season as relievers.²

It’s also easy to understand because it pegs to a base value of 100 for the league average. Higher than 100 is better, lower than 100 is worse. Makes sense, right?

What does Stuff+ think about the Braves?

I went over to FanGraphs and pulled every Braves pitcher with ten or more innings³ last year:

Do you see why I’ve been so high on Spencer Schwellenbach?

Atlnata’s young hurler has the highest Pitching+ on last season’s roster at 113 and his Stuff+ is second-best for starters, behind only reigning Cy Young winner Chris Sale.

His elite four-seam fastball (112 Stuff+) sets up another elite pitch in the slider (113) and that’s backed up with several other quality pitches in a curveball (101), changeup (100), and sinker (98).⁴

Side note: You see how almost everything Max Fried throws was either 3-8 points above average or awfully close to it? THAT’S why he got paid this offseason by the Yankees.

Chris Sale’s fastballs aren’t bad (101), but his slider (118) is the real star of the show and the best individual pitch for any starter on the roster (and one of the best in all of baseball). This mirrors his Statcast Run Values - his fastballs combined to finish at +1 Run Value but the slider was 100th percentile at +24.

Reynaldo López has some interesting trends, starting with the overuse of a fastball that grades out as “only” a 91 on Stuff+ and less-than-ideal use of a well-above-average slider (108) and changeup (104). Do you see why so many models also think he’ll take a small step back this year?

The flip side to that argument is this: Don’t worry about Reynaldo López having a 91 on his fastball because of how much he ramps up the velocity when he needs it (two outs, runners on, etc). Those are situations when he uses the fastball much like a reliever would…and back in 2023, he had a 104 Stuff+ on the heater and a 100 in 2022.

Sorting by just starts⁵, we get some interesting info on Grant Holmes: His fastball grades are poor (81) but he makes it work with an above-average slider (102) and curveball (103). If there’s a concern with him in the rotation, it’s the fastball. He’ll need to maintain better velocity as a starter for it to work long-term.

You can see why the Braves are high on Daysbel

Joe Jiménez is a Stuff+ darling with an overall 105 grade (110 fastball, 103 slider) who’s going to be out for most of this season after offseason knee surgery.

Enter Daysbel Hernández.

Stuff+ thinks his combined score of 113 was the best on the entire roster, although that also came with a relatively low Location+ of just 94 and a respectably above-average 105 Pitching+. If he can be just a bit more precise with his locations, that heater and slider combo can absolutely eat for Atlanta out of the pen this season.

We don’t talk enough about Aaron Bummer’s ELITE stuff

The highest Stuff+ score on the entire roster was Daysbel’s 113.

The second-highest was Aaron Bummer’s 111.

Despite a relatively low fastball velocity of 93.2 mph, Bummer’s fastballs sit at exactly league-average (100) and virtually everything else (minus the 83 changeup, which he throws only 1% of the time⁶) is some grade of above-average (sinker, cutter) to “holy shit” (slider, curveball). Does that late 2023 trade make more sense now?

I still don’t know how Dylan Lee does it…

…but he somehow does the dang thing.

That man’s got a 105 Stuff+ despite throwing a 92.4 mph fastball (that still individually grades out as a 100), mostly because of his dominant (112) and heavily-used (55%) slider.

As I said on the pod last week, you don’t have to understand HOW it works to acknowledge that it DOES work.

Throw it again!

Oh, and because we talked about it yesterday, newly signed Buck Farmer has a slider with a 113 Stuff+ grade. Let’s throw that some more, yeah?

New pitches might change this

We got some reporting yesterday that AJ Smith-Shawver has added a cutter, while Hurston Waldrep is bringing back his curveball. Curious to see where their Stuff+ numbers come in this season - their MLB samples were so small last year (4.1 for AJSS, 7 for Waldrep) that there’s not much we can learn from those numbers.

1. Either the book or the movie, your choice

2. Stuff+ by itself only takes about 80 pitches to stabilize, but Location+ needs about a 400- pitch sample before you can get to a similar level of stability. Stuff+ is also sticker year to year, i.e. your stuff might always be filthy, but your ability to throw it in the zone fluctuates more from season to season than the quality of your stuff

3. I chose 10 innings because the next cutoff was 20, but Daysbel Hernández had only 18 innings in the model and I wanted him included. You’ll see why.

4. Schwelly also gets high marks for his splitter (112 Stuff+), which isn’t displayed on the chart because he throws six different pitches…which as listeners to the podcast know, is the way to my heart.

5. Moving from starting to relief and vice versa is usually an 8-point change in Stuff+ overall (12 points on fastballs), with one standard deviation being ten points. Scouting for guys with above-average Stuff+ on multiple pitches as relievers and doing that subtraction manually is one way that teams (and writers) have identified candidates to convert to the rotation.

6. 11 times in 974 overall pitches in 2024