As the 2025 MLB season winds down for fans of MLB teams well outside of playoff contention, it can be easy to forget about the results on the field for these final games, as it’s more about enjoying watching the club before they go on hiatus for 5 months. What you may not know, however, is that the club’s performance over this final month can actually provide us with critical insight into the team’s future, specifically for the 2026 season.
I took the wRC+ and FIP- from September of every Nationals
club (2005-2024) and compared it to the full-season wRC+ and FIP- of every Nats club (2006-2025) in order to better understand how the performance at the end of one year translated onto the field in the next year. Starting with the offensive side of the ball, the results were rather unsurprising, with bad Septembers often leading to bad full seasons the following year (Often times from the 2020s Nationals clubs, who offenses have been bad most years) and good Septembers often leading into good full seasons the following year (Often times from the late 2010s Nationals club, who’s offenses have been good most years).
The most interesting part of the data, and the most relevant to the Nationals currently, is the difficulty of predicting the following year’s wRC+ when an offense is bad in the September prior, as sometimes they can come back the next year looking great, and sometimes they can look really bad. Take, for example, the 2018 Nationals offense, which finished September 2017 with an 83 wRC+ (the 4th worst offensive September in Nats history), and bounced back with a strong 101 wRC+ that next year. There is also the 2025 Washington Nationals, who finished September 2024 with an 82 wRC+ and currently possess an 85 wRC+ as a club in 2025. While the majority of the time the bad September offenses will be bad the following season, there are also times when they break out in a big way.
The pitching numbers, however, paint a much clearer picture. September FIP- is a strong indicator of FIP- the following season, often being right on the money about how a staff will look the next season. The good September staff tend to remain strong the following year, and the bad September staff tend to be pretty bad again the following year. The most interesting part, and, again, the most relevant for the Nats currently, is that past Nats clubs that have had similar September performances to the 2025 Nationals staff have often been much improved the following season. Of the 4 past Nats teams to be within 3 points of the 2025 September Nats FIP- of 110, 2 of them went on to be league average or better pitching staffs the following year, with another improving by multiple points to be close to league average, and just one staff regressing.
So, where does that leave the 2026 Washington Nationals? With an 85 wRC+ and a 110 FIP-, they sit in muddy waters in terms of the Nationals teams they sit around, but that doesn’t mean hope is lost. Offensively, most Nats clubs with bad Septembers tend to have poor offenses the following season, but that isn’t always the case, as some offenses are able to find their groove, such as the 2018 Nats. The Nationals’ lineup seems likely to add 1-2 pieces entering 2026, and when accounting for growth from a majority of the youngsters on the ballclub, I would be willing to bet the 2026 Nats lineup will be one that improves, not stays stagnant or regresses compared to the September priors numbers.
On the pitching side, there are some signs of improved fortunes for the Nationals entering 2026, as the combination of historical trends, free agent acquisitions, and a new coaching staff all point towards next season’s pitching staff being a much stronger unit than this year’s. The key for the club going forward needs to be building pitching depth so that when current rotation members, such as Jake Irvin and Mitchell Parker, fall short of expectations, there is a viable option to replace them instead of being forced to use them every 5 days and hoping they can turn it around.
Overall, while September numbers certainly don’t define who the Nationals are going to be the following year, they can offer us insight into who they could become based on past trends. If the Nationals have playoff aspirations in 2026, the best way they can do that is by following the trend of an improving staff after a middling September, and becoming an outlier among offenses with weak Septembers. With how much change is coming soon to the ballclub, both on the field and off, anything is possible.
