The 2021 season has not gone the way Aaron Nola and the Philadelphia Phillies had envisioned for the starter. Nola, who entered the season as the 1 of a strong 1-2-3 rotation, sits with a 4.22 ERA and a 5-4 record in 15 starts. He allowed six runs, one short of tying a career high, in just 2 ⅓ innings pitched in his last start in San Francisco. It was the shortest start of Nola’s seven year career. Nola now has a 5.85 ERA through four starts in June. 

So what happened to the usually dependable Phillies ace? Why is Nola struggling to limit runs this season and failing to pitch deep into games on a consistent basis?

Fastball command

Nola’s keys to success are to establish fastball command early to both sides of the plate and then to attack with offspeed, primarily his curveball. When Nola commands his fastball, he can run it with two seam movement where it starts way off the plate but comes back towards the plate late as pictured below.

That pitch can be extremely effective to both righties and lefties when Nola has it working to both sides of the plate as he did in 2020. However, so far in 2021, Nola’s command has been erratic. He’s missing middle and up with his fastball, resulting in a .263 batting average and a .475 slugging percentage against. The expected slugging of .590 hints that Nola has actually been somewhat lucky in how hard his fastball is getting hit. For comparison, hitters logged a .135 BA and .327 SLG in 2020 within an expected slugging of .433. The whiff percentage is also down on the pitch in relation to last season. Nola’s fastball is causing hitters to swing and miss 25% of the time, whereas it was just a hair under 30% last season. 

So what does that mean? It means that Nola isn’t locating his fastball to the corners of the plate but rather leaving it out over the middle too much and it is getting hit. Here is an example of where the catcher sets up low and outside but the pitch runs way back inside and up across the plate to William Contreas who promptly hits it for a home run.


No “Snap” on Curveball

Nola throws two versions of a curveball. One has a more 12-6 spin on it, meaning it starts high then drops low. The other has more of a knucklecurve action to it where it starts somewhat straight before dropping in a tighter spin. Here he is in September of 2020 spinning nasty curveballs against the Nationals.


You can see the “snap” that Nola has here on the pitch. This allows him to fool hitters with its speed and its sharp downward action. However, this year, Nola is missing much of that snap and is hanging the pitch up over the plate, effectively putting it on a tee for hitters. Look at this curveball that Brandon Belt demolishes for a home run in San Francisco on June 19th.


This pitch rolls to the plate and is left belt-high, right in the perfect spot for a hitter like Belt to crush it. Below is another one that has more break but is still left middle-up for Danny Santana who hits it for a home run on May 21st.


The curveball is Nola’s best put away pitch, but he isn’t putting hitters away with it. In fact, it has a put away percentage of just 27% of the pitches thrown, a dramatic decline from 40% last season. That means Nola is striking out half the batters he did last season on his curveball. 

Struggles with two outs

Perhaps the most baffling part of Nola’s 2021 has been his inability to get the third out of an inning consistently. Opponents have an .805 OPS against Nola with two outs in an inning, higher than with no outs (.753) or one out (.624). Seven of the 12 home runs Nola has surrendered this year have come with two outs. Even more staggering, 12 of Nola’s 19 walks on the season are with two outs in an inning. He has almost doubled his walk total with two outs already on the board. Nola has allowed 19 runs with one out or no outs in an inning to 230 batters and 22 runs on just 98 batters with two outs. 

Road Woes

Nola, much like the rest of his team, has struggled mightily on the road in 2021. In eight starts on the road, Nola has a 6.00 ERA and a batting line of .288/.346/.503 against. At home, Nola has a 2.49 ERA in seven starts with an opponent’s slash line of .218/.263/.339. He has surrendered eight home runs on the road and four at home. His career splits show the same disparity, with a 4.21 ERA on the road and a 2.94 ERA at home. Nola’s rough starts on the road are no doubt a large factor into the Phillies team record of 13-23 on the road this season.