In awe of Aaron Nola and his evolution

Tuesday night in Philadelphia, Aaron Nola struck out 12 San Francisco Giants hitters. He also allowed just four hits – one double and three singles – and walked nobody. He was sharp. He was hard to beat. He finished the evening with a 3-1 lead, which eventually became a 4-2 victory and his fifth personal win of the season.

Here are Nola’s numbers after Tuesday’s performance:

8 G, 52.2 IP, 5-1, 2.05 ERA, 47 K, 11 BB

While they look fantastic, those numbers don’t necessarily tell the story of Aaron Nola in 2018. Of course, basic counting statistics and foundation indicators like ERA are almost never enough. We now can investigate how much contact a pitcher’s pitch generates, and what typically happens when one of his pitches gets put into play. We now can find the spin rate of his breaking pitch, then use that to figure out why his strikeout rate is higher than in the past. Or, to step back, we can find his strikeout rate. These kinds of tools weren’t readily available (as in, you needed a calculator and a formula and time) 20 years ago, but here we are, and the tools help us tell a more layered story.

The story of Aaron Nola in 2018 starts with a premature evacuation from opening day and a second start that wasn’t ideal for fans, either. Then he struck out just two Braves in a hard-luck loss, and fans started to wonder why he wasn’t striking out a lot of hitters. Maybe it’s because the Braves just don’t strike out, but we didn’t see that – instead we saw 15 strikeouts in 24.1 innings and scratched our heads. Meanwhile Nick Pivetta and Vince Velasquez were whiffing everyone in existence early on.

But Pivetta and Velasquez slowed down and regressed, and Nola started striking out more batters. He’s now striking out 23.9 percent of them, which is close to his career average (24.8 percent). But with that, he’s also walking fewer batters than usual (5.6 percent as opposed to a 6.4 percent average). And it seems, at least over the last month, as if he’s improved there; in his first three starts he walked eight batters, but since (five starts), he’s only walked three.

Batters are making contact at the same rate as before (75.7 percent) but Nola is getting more swinging strikes (11.9 percent).

The big reason all of this is looking better: the changeup.

We know Nola carries an elite-level curveball and two semi-average fastballs (a four-seamer and two-seamer). He also used to carry a below-average changeup, which he threw sparingly (typically less than 10 percent of the time). Last year it morphed into an average changeup, and he threw it a little more (about 15 percent of the time).

This year the changeup is arguably his best pitch. And he is suddenly throwing it a lot. Since the April 21 game against Pittsburgh, Nola has thrown his changeup more than 20 percent of the time. In his start against Miami on May 2, he threw it nearly 30 percent of time, exactly as much as his four-seam fastball. Last night he threw the change 22.9 percent of the time to 26.6 percent for the curve and 38.5 percent for the fastball.

The two-seamer (or sinker) has been the victim of this changeup renaissance. Once Nola’s preferred pitch (2016 to early 2017), the two-seamer is now being thrown about 15 percent of the time.

Nola would get whiffs with the changeup in the past, but it was also susceptible of being hit (.319 BAA, .428 SLG before 2018). In essence, it was his riskiest pitch. Now the changeup has a .209 BAA and .209 SLG, with all nine hits against the pitch being singles. And he’s getting whiffs on the pitch 24.2 percent of the time, far higher than any of his other pitches.

There’s a recent adage in the baseball community that statistics can’t be truly scrutinized until Mike Trout is atop the WAR leaderboard. Well, Trout has 3.3 WAR at Baseball Reference, leading that list, and he has 2.9 WAR at Fangraphs, leading that list. So I suppose we can start taking the numbers seriously.

Fangraphs has Nola, with his improved changeup and fuller arsenal, ranked seventh among all pitchers with 1.7 fWAR. The names above him are: Gerrit Cole, Max Scherzer, Luis Severino, Justin Verlander, Jacob deGrom and Rick Porcello. These are all very good pitchers.

According to Baseball Reference, Nola has 2.4 rWAR. Here are the pitchers above him:

Okay, let me rephrase that: Here are the players above him: Mike Trout, Mookie Betts.

We’re seeing evolution in real time. Typically young pitchers have to morph from “throwers” to “pitchers,” and typically that means adding a third pitch or fourth pitch that rounds out their arsenal. We met Cole Hamels (the last great homegrown Phillies starter) as a fastball-changeup pitcher with a working and bad curveball. After getting by for a while with that arsenal, he realized he had to evolve. He grew into a “pitcher” by adding a cutter, which turned him into a top-level performer. Then he dialed back the fastball and added a sinker. Then the curveball got better and he threw that more, sometimes more than the changeup. Today’s Hamels is far different from the guy we saw in 2007. He evolved.

Aaron Nola, I guess, was fastball and curveball with a bad changeup. Essentially the changeup for Nola is the cutter for Hamels. It’s getting better. He’s using it more. It’s making him more complete.

Hamels was 26 when this happened. Aaron Nola is 24.

Also, Aaron Nola is, according to some metrics, the best pitcher in baseball in 2018. He is 24.

(Stats via Brooks Baseball)