After a 13-3 drubbing of the Miami Marlins on Sunday afternoon, the Washington Nationals have won seven of their past eight ballgames. A Mets loss later in the evening helped to cut the difference between the NL East's top two teams to six games with thirteen remaining. Over the past seven days, the Nats have cut three and a half games off of that deficit. If they can repeat that feat and trim three more games off the deficit in the next ten games, the Nats can give themselves a shot as they head to New York to close the regular season.
The swing has been evident beyond simple wins and losses, though. As the Nats won by ten runs yesterday and the Mets lost by nine, the season-long run differential between the two teams continued to see a massive swing. As recently as two weeks ago, the Mets held a double digit lead over the Nats in run differential. Times have changed. The Nats and Mets entered Sunday's games in a virtual dead heat, with the Nats holding the smallest lead imaginable (+68 for Nats, +67 for Mets). They now find themselves twenty runs apart, with a significant edge for the Nats in the category.
Of course, right there, we can see how run differential and the Pythagorean W-L Theorem don't tell us everything. The Nationals Pythagorean record would be 83-66, one game worse than the Mets actual record and five games better than the Nats actual record. The Mets, on the other hand, would be 81-68 by Pythagorean W-L... two games worse than their actual record. If the games were just played on paper with the runs scored/allowed being equal in all games/situations, the Nats would be two games up in the division, rather than six games down.
One of the things that takes away the relevance of the Pythagorean record a bit is a swing like the one we saw yesterday. At the end of the day, the Nats were +19 in run differential in comparison to the Mets (+10 for the Nats, -9 for the Mets), but the reality is that all of that just represented one game for each team. By Pythagorean record, it shifted the expected winning percentage by quite a bit more than any one game could.
Simple math (1/162) tells us that each win in the standings is going to be worth .00617 percentage points in the standings. However, the Pythagorean standings saw the Nats winning percentage improve by .00714 on Sunday. The Mets Pythagorean win percentage decreased by .00806. Per Pythagorean, the Nats won about 1.15 games on Sunday, while the Mets lost 1.30 games.
While run differential and the Pythagorean W-L record certainly isn't perfect in terms of evaluating what has happened, it's not something that should be completely ignored either. Of the eight teams in the National League with a positive run differential, seven of them are above .500. Just Arizona (+12, 71-78) is below .500. Between both leagues, just one team (Texas, -7, 80-69) that would currently reach the playoffs has a negative run differential.
While teams can point to wins in one run games or close (non-one run) games as something that can help separate them from competitors in the standings, those "clutch" wins are less likely to provide consistent success than simply outscoring your opponents by a wider margin on average. If a team is typically eking out wins by one or two runs when they're on the right side of the ledger but losing by four or five runs when they don't come through, things are likely to even out eventually. The same goes for a team that loses a handful of close games and dominating when they win. It seems far more likely that their luck is going to change in those close games since they've shown that they're capable of going off at any moment.
All of this is just a long-winded setup to what the Nats have done over the past few weeks. Throughout most of the year, we've pointed to May as one of the more dominant stretches that the Nats have had since moving to D.C. They went 18-9 in May this season, which was actually 21-6 in a calendar month from April 28 through May 27. During that dominant May, the Nats outscored their opponents 125-105. This would have been good for a .586 Pythagorean W-L Percengage, or 15.83 wins (let's round it up to 16 for a 16-11 projected mark). That's pretty strong, but it's nothing like what the Nats have done in September so far.
Thus far in September, despite a five game losing streak at one point, the Nats have outscored their opponents 117-69. That's a +48 run differential in their first nineteen games this month. The Nats Pythagorean Win Percentage thus far in September is .742! Their projected September record (14-5) is actually a couple of games worse than their current September record (12-7), but a five game losing streak and a handful of lost leads by the bullpen will do that to you.
The pitching has been fairly strong, as the Nats 3.28 ERA so far in the month of September ranks fifth in the majors. The offense is what has really supported this late season run, though. The Nats offense currently leads the majors with 117 runs in September. No other team is within ten runs of the Nats so far this month (Cubs, 106). In short:
Dominant Hitting + Dominant Pitching = Big Run Differential = Wins
There are thirteen games remaining in the season. The Nats still need some help from the Braves, Reds, and Phillies, but anything can happen. The way that this team is playing right now, they're capable of making up enough ground on the Mets to make that final series in Citi Field mean something. They're finally firing on all cylinders, and it's fun to watch.
Keep fighting Nats!