Why does Philadelphia Phillies RHP Aaron Nola struggle in September?
For the third season in a row the Philadelphia Phillies found themselves entering the month of September with solid odds to make the postseason, and for the third season in a row they were unable to lean on their ace Aaron Nola to help get the job done. His most recent late-season collapse came in the final game of the 2020 regular season, where the righty allowed three runs through just 3.2 innings.
The Phillies inability to see October baseball the last three years is undoubtedly not on Nola’s shoulders, as for the most part he’s been a very, very good regular season pitcher. However, his end of the year collapses have come all too familiar to fans as of late, and it’s concerning. A team is supposed to be able to lean on their ace when the pressure is at its highest, and the Phillies have been unable to do that with Nola quite yet.
Nola was quite possibly having the best statistical season of his career this year, and yet still faltered when the month of September rolled around. With that in mind, I did some digging on what could be responsible for the routine falters.
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For starters, this isn’t a small sample size. Nola has made 139 total starts in his career thus far, and the statistics quite overwhelmingly support the theory that September is a bad month for him. His average ERA jumps from 3.47 to 4.28, and his average WHIP jumps from 1.164 to 1.307.
When compared to his other monthly splits, the month of September is the worst for Nola in terms of hits allowed, walks allowed, total bases allowed, opponent slugging %, and opponent OPS. Almost 850 innings into Nola’s career and it’s pretty clear that September just ain’t a good time for the Louisiana born right-hander.
One of the most common theories thrown out there is that Nola struggles in cold weather, which on the surface, appears to check out. His numbers in March and April aren’t always the prettiest, and he seems to get better as the heat rises.
HOWEVER, what really caught me by surprise is that June is actually Nola’s worst statistical month in terms of ERA, WHIP, and opponent batting average. Yes, even worse than his ever talked about September woes.
Nola’s June struggles aren’t ever really talked about, most likely due to the fact that he ends being borderline un-hittable during the months of July and August. Any sort of mishaps earlier in the summer are quickly forgotten when he turns it up to a different level for the heart of the season.
With the weather theory somewhat debunked, I thought maybe it had to do with overall fatigue. However that idea was pretty much crushed during this year’s season, as he made just six starts before September rolled around.
Does Nola just not perform well in the clutch?
Is it just an overall lack of a “clutch gene”? Again, probably not.
When looking at some of Nola’s “clutch stats” (2 outs RISP, late & close, tie game, etc) pretty much none of them stray away from the norm. In fact a majority of his clutch stats are actually better than his usual career averages, leading one to believe that he actually thrives in such moments.
Nola’s “high leverage” opponent OPS is actually a full eight points lower than his “low leverage” opponent OPS. Quite an eye-popping stat considering it’s almost always the opposite with pitchers.
In 2018 and 2019, two seasons where Nola really struggled down the stretch, his opponent batting average with RISP were .169 and .117. Ridiculously low numbers.
Nola’s numbers against rival NL East teams are also consistently solid across the board, with his worst average ERA coming against the Nationals at 3.89 (still pretty good). Nola appears to actually play up to high pressure situations, especially against division rivals, making him surprisingly appear more “clutch” than not.
So if it’s not weather related or clutch related, what could possibly be the reason for Nola’s routine late season struggles? One career split that I did end up stumbling upon was his performance when operating on short rest. When Nola only gets four days of rest, his ERA jumps up to 4.34, compared to it being 2.71 when on five days of rest.
Considering the fact that the Philadelphia Phillies have run him on short rest in the past in an attempt to sneak into the postseason, this could at least be a piece to the puzzle.
Outside of the short rest factor, I really couldn’t find anything else to explain these end of the year “collapses”. The fact that June is statistically a worse month for Nola than September was fairly eye opening, as it could be sign that the Philadelphia Phillies fanbase has simply created a false narrative. Nola doesn’t exclusively struggle in September, signaling that he could just be a streaky pitcher.
There could be a small mental block happening with Nola when it comes to these end of the year starts, as he knows he pretty much has to be perfect for his team to have a shot. In the past he was the only serviceable starter the club had, and he knew that his starts were the only way his team could secure wins. Having Zack Wheeler around this year helped, but the team’s historically bad bullpen honestly probably made the pressure worse than before.
If we’re talking analytics and numbers, Nola should in theory actually thrive in these high-leverage situations. I hate to end this article without a definitive answer, but I’m really not sure what the conclusion to be had is here. Avoiding games on short rest in the future would be a good starting point, but in all reality this team just needs to find a way into the postseason to see what their ace looks like in a real high stakes environment.
If Nola gets rocked in his first career playoff start, then we can have conversations about him being an “un-clutch” pitcher. If he throws 7.0 innings of one-run ball, then we can probably put all this noise to rest.