A year ago, Aaron Nola was one of the best pitchers in baseball. His 3.01 FIP was very good, his 2.37 ERA was even better, and his 5.4 WAR was fourth in the National League and helped him to a third-place finish in the Cy Young voting. After four starts this season, Nola pitched like one of the worst pitchers in baseball with a 6.25 FIP, a 7.45 ERA, an ugly 13% walk rate, and a -0.2 WAR that ranked 74th out of 77 qualified pitchers. At that time, Dan Szymborksi diagnosed Nola’s issue with walks and homers and noted the following:

At least in the early going, batters seem to simply be taking a more passive approach to Nola after his breakout 2018 season, and he hasn’t adjusted. And he’s getting away from some of the things that he did successfully in 2018, such as daring to throw curves to lefties when behind in the count (he’s dropped from 39% to 20%). Batters are more patient and Nola’s been more predictable.

Since that time, Nola has essentially returned to form. He had one more bad start where he gave up two homers but encouragingly struck out nine batters against one walk. Since that start, Nola has taken the mound nine times and his FIP has been 3.30, a 76 FIP- in this run-scoring environment and very close to the 73 he’s put up over the last three years. His ERA is a very good 3.48, and though his walk rate is slightly elevated at 10%, his 26% strikeout rate is right in line with last season. In his piece, Szymborski produced a table showing the cause of Nola’s high walk rates. Batters weren’t chasing pitches they used to and they were making contact when they did. Here’s the bulk of that table, with Nola’s work through the time of Dan’s piece on April 18 and since then.

Aaron Nola Plate Discipline Year K% BB% O-Swing% Z-Swing% Swing% O-Contact% Zone% F-Strike% SwStr% 2016 25.1% 6.0% 29.5% 55.7% 42.2% 61.5% 48.3% 60.7% 9.6% 2017 26.6% 7.1% 29.4% 60.8% 44.5% 59.3% 48.2% 64.4% 10.8% 2018 27.0% 7.0% 33.2% 64.2% 47.0% 60.9% 44.7% 69.4% 12.4% Thru 4/15/19 21.8% 12.6% 25.5% 55.4% 38.4% 70.0% 43.0% 48.3% 8.4% Since 4/15/19 26.8% 9.2% 30.3% 57.0% 41.1% 61.8% 40.4% 62.4% 9.2%

Nola isn’t quite repeating what he did a year ago, but he’s not too far off either. He’s throwing fewer pitches in the strike zone and he’s not getting as many swinging strikes, which is something of an issue, but when hitters swing at pitches outside the zone, they are whiffing like they used to. Getting a lot more first strikes is a good thing for Nola, but even better, he’s actually finishing off batters once he gets that first strike.

A year ago, Nola was a good pitcher regardless of whether he got the first strike. When he went 0-1 on a hitter, Nola put up a 2.45 FIP. This is an impressive number, but it only put Nola at the edge of the top-third among starters. Nola separated himself from most pitchers in two ways. First, he got the first strike so often that he recorded the fifth-most outs in baseball after a count reached 0-1. Second, he was better than nearly all pitchers when he threw a first-pitch ball. Nola’s 3.44 FIP after a count reached 1-0 was fifth-best in the game behind only Jacob deGrom, Miles Mikolas, Chris Sale, and Patrick Corbin. This season, Nola started the year unable to throw a first-pitch strike at a high rate, and when he did get that first pitch strike, he followed up with hittable pitches instead of putting batters away. In his first four starts, Nola got to an 0-1 count 36 times. Five of those 36 players hit home runs, another two drew walks, and another six reached base via a hit.

If we limit our study to only the pitches Nola threw on 0-1 counts in his first four starts, we see a concentration in the middle of the plate.

Here’s one such pitch.

We could chalk it up to randomness, but here’s where Nola has thrown his pitches in 0-1 counts since April 15:

It certainly looks like Nola is hitting his spots a lot more. The results of the pitches are below.

Aaron Nola on 0-1 Counts Called Strike Swinging Strike Foul Ball BIP Out BIP Hit Thru 4/15/19 10.8% 16.2% 21.6% 29.7% 10.8% 10.8% Since 4/15/19 15.5% 14.7% 13.2% 42.6% 10.9% 3.1%

Nola is giving up some strikes here by being finer with his pitches, but he was probably a bit too hittable at the beginning of the season. Hitting the corners means more taken strikes and not as many hard-hit balls. The strategy is working. Since April 15, Nola has struck out more than 40% of the batters he’s gotten to 0-1 counts, putting up an 0.89 FIP, fourth-best among starters with at least 100 batters faced behind only Frankie Montas, Carlos Carrasco, and Sale. When he’s gotten to 0-2 during that time, he’s struck out 32 of 57 batters. While he was unusual last season in posting really good 1-0 count numbers and just solid 0-1 count numbers, he’s been a bit more like a typical pitcher of late, excelling after getting the first strike but struggling a bit when falling behind in the count. If he wants to get back to where he was last season, he’ll have to get better at battling back once he gets behind, but Nola’s overall line doesn’t represent how well he’s been pitching lately. Here’s his 9-game rolling FIP over the last few seasons.

On the year, Aaron Nola has a 4.22 FIP and a 4.58 ERA, but he hasn’t been pitching like a mediocre pitcher for some time now. He had a rough start to his season, and his high BABIP is some indication that he’s still having some bad luck when it comes to his ERA, but his strikeouts look a lot like the Aaron Nola we’ve come to expect. The home run numbers look good too, and while the walk rate is slightly above what we would want to see, it appears he is adjusting to hitters trying to take advantage of his strike-throwing, and he’s been more precise with his pitches. Nola’s overall line is deceiving, as he’s not struggling. In fact, he’s back to being the ace the Phillies need.