Whenever a Major League pitching staff suddenly transforms from a 4.50 ERA tire fire into one of the stingiest rotations in the league, television broadcasts love to talk about “pitching with conviction” and “great clubhouse chemistry.”
Those things are nice, but what actually happened when Andrew Bailey took over the Boston Red Sox pitching coach office was much simpler: he told half the roster to stop throwing their four-seam fastballs.
The “Dead Zone” Trap at Fenway
For the better part of a decade, baseball’s analytics wave told every pitcher the same thing: spin your four-seamer as hard as you can and throw it at the top of the strike zone.
That works great if you’re throwing 99 mph with 19 inches of Induced Vertical Break (IVB) like prime Gerrit Cole. But if your four-seamer sits around 93 mph with 14 or 15 inches of IVB, you don’t have a weapon; you have a “dead-zone” fastball. It doesn’t rise enough to miss bats, and it doesn’t sink enough to induce ground balls.
At Fenway Park, throwing a dead-zone fastball to a Major League pull hitter is just an efficient way to dent the advertisements on the Green Monster.
Bailey’s staff took immediate action:
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Four-seam fastball usage dropped by nearly 14 percentage points across the team.
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In their place, pitchers were handed pitch grips that generated sideways movement: sweepers, cutters, and splitters.
The Horizontal Fork: 30 Inches of Separation
The real magic of the new repertoire was horizontal tunneling.
Consider a right-handed pitcher who can throw both a running sinker (tailing 14 inches arm-side) and a sweeper (breaking 16 inches glove-side). If both pitches come out of the same release point, they look nearly identical for the first 25 feet out of the hand:
A hitter has roughly 150 milliseconds after release to decide whether to swing. When two pitches can end up separated by two and a half feet across the plate, guessing wrong means either waving at air two inches off the outside corner or fouling a sinker off your shin.
Attack on 0-0
The second half of the recipe was eliminating “wasted” early pitches.
Across baseball, the difference between an 0-1 count and a 1-0 count is night and day. Hitters’ expected run production drops by roughly 100 points of wOBA the moment they fall behind in the count. Boston began pounding the strike zone early with offspeed pitches, stealing 0-1 strikes against hitters who were sitting on first-pitch fastballs that never came.
Once you have a hitter in an 0-2 or 1-2 hole, the battle is basically won.
You don’t always need to spend $300 million on flame-throwing aces to fix a pitching staff. Sometimes you just need to look at the guys already on your roster, figure out what their wrists naturally do well, and stop throwing flat fastballs into right-handed power alleys.