Air resistance in the playoffs has shot up to the highest level since 2016, causing fewer homers. Multiple lines of evidence suggest that the postseason baseball is totally different than the one used in the regular season. baseballprospectus.com/news/article/5… 
This is data coming from MLB's own pitch tracking system, and I confirmed it by looking at how many homers you would expect to see based on exit velocity+launch angle+park effects. There have been about *50%* fewer home runs than expected.
That includes a few no-doubters, including a couple in the Dodgers-Nats series. Drag has a much more significant effect on the marginal home run cases, though--the balls between 20-70%ish home run probability. These just aren't carrying like they used to.
MLB may have been afraid of the juiced ball deciding a playoff series when what would have been a weak flyout went over the fence, but instead they've ended up with the opposite: hits we thought were certain dingers dying at the track instead.
The speed and magnitude of the change and the timing of it aligning so perfectly with the playoffs makes it much harder to believe this was a random manufacturing accident. In the past, drag has drifted around slowly during the course of the season, but this was massive & abrupt.
A lot of people are repeating the same question so, no, it's not caused by weather:
1) The drag measurements correct for temperature and pressure
2) October temperature so far has actually been higher than the season average
3) Temp just doesn't make that big of a difference.
1) The drag measurements correct for temperature and pressure
2) October temperature so far has actually been higher than the season average
3) Temp just doesn't make that big of a difference.
