The story of this World Series, to this point, has been Cleveland’s dominance over Chicago’s hitters. During the regular season, the Cubs had the best offense in baseball, once you adjust for the fact that they didn’t have the advantage of the DH, and they regularly pounded their opponents with great hitters and a deep line-up. In this match-up, though, their bats have gone quiet, as they have hit just .210/.281/.311, scoring all of 10 runs in the first five games.

The easy way to explain Cleveland’s success has been to point to greatness of Corey Kluber, Andrew Miller, and Cody Allen, and note that those guys have thrown nearly half of the team’s innings in the series. And it’s certainly true that the Tribe have leveraged their best arms to maximum efficiency, making it quite difficult for the Cubs to rally against inferior pitchers. But there’s more to this story than simply Terry Francona’s bullpen usage; the team is taking apart with the Cubs offense with a systematic plan to pound them with breaking balls.

During the regular season, the Cubs saw a breaking ball — I’m just combining curves and sliders into one term to avoid classification differences — 25% of the time, right in line with the Major League average. In the World Series, though? Cleveland has thrown bendy pitches at the Cubs hitters on 34% of their pitches, which dwarfs the rate any team saw breaking balls during the regular season. While a nine percentage-point increase might not sound like a lot, it works out to about 15 more breaking balls per game, and those extra curves and sliders are making good Cubs hitters look silly.

You don’t need me to tell you about what this approach has done to Javier Baez, but the numbers are still staggering. He’s swung at nine of the 15 curveballs he’s been thrown in this series, and whiffed on seven of those nine swings. 12 of his 21 at-bats in the series have ended with a breaking ball, with six of them ending with him chasing a pitch out of the zone for strike three. Even when he has managed to make contact with a breaking ball, it’s been a weak groundball or an infield fly. The heavy bendy-pitch approach has turned the star of the NLCS into an automatic out.

This isn’t just about attacking Baez’s weaknesses, though. As Mike Petriello noted when previewing Josh Tomlin’s first start, the Cubs have had a curveball problem this year.

So Tomlin identified opposing strengths and weaknesses, and in those two curveball-heavy starts — both Cleveland wins — Tomlin managed to get through 10 2/3 innings while striking out 10 and allowing only three runs. Guess what: The Cubs may have a similar weakness. Lowest team exit velocity against curveballs, 2016

84.3 mph — Cubs

84.5 mph — Reds

85.1 mph — Yankees

86.2 mph — Giants / Phillies The Cubs have just a .201 average (the eighth lowest) on curves, and if you’re now rightfully thinking that you only worry about exit velocity and average when contact is made, well, Chicago had a 32.1 percent contact rate when swinging at curves — which is the lowest in the Majors.

The last part has been the issue Cleveland has exploited. In the regular season, the Cubs chased 35% of the breaking balls they were thrown out of the zone, but against the Tribe, that’s jumped up to 50%. While some of this is just the reality that Kluber, Allen, and Miller have really good breaking balls, and thus are harder to lay off, the Cubs willingness to expand the strike zone has played right into Cleveland’s plan to attack them with pitches they can’t hit.

That’s what made the Cubs fourth inning rally against Trevor Bauer so curious. Bauer was great through the first three innings, mixing the Kluber-esque front-door two-seamer with a curve he was locating, but in the fourth, he had to face the middle of the Cubs order. And he decided to challenge them with fastballs.

Leading off the inning, Kris Bryant saw three straight fastballs, launching the third one into the left field seats to tie the game. That was followed by a first-pitch fastball to Anthony Rizzo, who hit it into the ivy in right field. Having just seen his fastball get crushed on back-to-back pitches, he decided to try the breaking ball, but bounced one to Ben Zobrist, who is the one guy in the line-up least likely to chase a bad pitch. Then he missed with another fastball and a change-up, falling behind 3-0, before throwing Zobrist a 3-0 fastball, which was promptly lined into right field for a single.

Bauer did move away from his fastball-heavy approach after that, attacking Addison Russell with three curveballs in four pitches, and going after the team’s weaker hitters with more frequent breaking balls. But the Cubs had done their damage at that point, and taken a lead they wouldn’t relinquish.

Bauer probably won’t pitch again in this series, but if I’m Terry Francona, I’m emphasizing that inning to everyone else on the staff. The Cubs have not yet shown that they can stop swinging at curveballs out of the zone in this series, and there’s no real reason to throw them a steady diet of fastballs until they do.

As Petriello noted, Tomlin has reinvented himself as a breaking-ball guy of late, and I’d fully expect that he’ll continue to throw a curveball-heavy pitch-mix at the Cubs in Game 6. And if it gets to Game 7, the Cubs will probably have to beat Kluber, Miller, and Allen, and no one else, so you know that game is going to be full of breaking balls.

If the Cubs are going to win the next two, they’re probably going to have to figure out how to make the adjustment they haven’t made yet. Last night, Bauer gave them enough fastballs to get three runs in one inning. They shouldn’t do that again. Make the Cubs prove they can hit a curveball.