Make no mistake: The Cubs have good hitters overall. They produced baseball’s seventh-best Weighted Runs Created Plus this past season,3Among non-pitchers. and its 16th-most runs scored per game. And against all pitches (fastball or no), the Cubs tended to whiff less than average — 22.8 percent, against an MLB average of 23.3 percent.But velocity is the Cubs’ kryptonite. On top of their tendency to whiff against the hardest fastballs, Chicago also made a lot of weak contact, reflected by pop-ups and a low batting average. Even when the Cubs could bring the bat to the ball, they failed to do much with it.Maybe, too, the Cubs’ tendency toward whiffs was exacerbated by the low temperatures in New York. ESPN’s Jerry Crasnick showed that high velocity is especially effective in the postseason, due in part to the effect of October’s low temperatures. When you combine the Mets’ powerful arms with the pressure of the playoffs and 40-degree fall temperatures, perhaps we should have expected the Cubs to struggle with contact.(As for the Cubs’ pitching woes: Those have been much more unexpected, and much harder to explain.)The outlook for the Cubs is now grim, as only one team in MLB history has come back from a 3-0 deficit. Then again, that one team (the 2004 Boston Red Sox) was also battling a curse with the help of a front office run by Theo Epstein. We’ll have to see if Epstein’s team can pull off the same trick twice, but it’s safe to say that the overwhelming velocity of New York’s pitchers has put the odds firmly against it. Chicago’s worst fear has come to pass: The New York Mets lead the Cubs three games to none in the National League Championship Series. Scoring only five runs in three games, Chicago’s usually powerful bats have been held in check, and a series sweep may be imminent. What happened to a Cubs team that looked like the pennant favorite after winning the National League wild-card game?One oft–repeated explanation of New York’s dominance is that Chicago’s hitters struggle against quality fastballs. According to this theory, that weakness is magnified against a Mets rotation headlined by three of the hardest-throwing pitchers in baseball: Noah Syndergaard (average fastball velocity: 97.7 mph), Matt Harvey (96.5) and Jacob deGrom (95.8). When New York dials up the heat, Cub bats wilt.Here at FiveThirtyEight, there’s nothing we love more than taking down faulty narratives. But this theory does seem to be borne out by the data. While the average MLB hitter whiffs at 96 mph fastballs 22.8 percent of the time,1Using data from PitchInfo from the 2015 regular season. the average Cubs hitter swings and misses 25.7 percent of the time against the same pitch type and velocity.2To get these numbers and generate the following chart, I modeled whiffs with a binomial logistic regression that incorporated count and fastball velocity.