Stats Pinpoint Exactly When Astros' Sign-Stealing Likely Started in 2017
By Sean Facey

As the days of the offseason slowly drag on, evidence of sign-stealing by the Houston Astros continues to mount.
Somehow, their chances of clearing their name took yet another big hit with this latest revelation. A simple look at the numbers indicates that the Astros' strategy, which likely started in mid-May of the 2017 season, paid immediate and blatant dividends.
The Astros' sign-stealing didn't start at the very beginning of the year. It kicked in starting in late May, and the Astros offense jump-started at almost the exact same time. https://t.co/w5q70HNhH0
— Rob Arthur (@No_Little_Plans) November 22, 2019
In the middle of May of that year, the Astros' team whiff rate takes a noticeable dive almost exactly around the time that the first audible noise from the dugout can be heard on video. It dropped from approximately 28% through the first month or so to around 21%, and it stayed there for the rest of the year.
But it doesn't stop there. The drop in swinging strikes also corresponded with a massive spike in the Astros' offensive production.
? @No_Little_Plans Alert?
— Craig Goldstein (@cdgoldstein) November 22, 2019
It looks like the Astros' sign-stealing efforts began in earnest in mid-May 2017. Let's see if anything ch-OH MY GODhttps://t.co/kDaOvAoBM4 pic.twitter.com/cefu1eY7xH
Their team slash line prior to the first audible noise was .272/.340/.425 ,according to Baseball Prospectus. By the end of the season, however, they were slashing .282/.340/.478 as a team, sporting a monstrous increase in power production.
After all, it's much easier to drive an off-speed pitch when you know that it's coming.
In fact, reviewing the last seven years of baseball, no team (out of 209 others) ever made as big an improvement after the end of May in both metrics as they did. And they also improved their exit velocity, launch angle, and raw triple slash figures to boot.
— Rob Arthur (@No_Little_Plans) November 22, 2019
All this does is further incriminate Houston. The numbers mean that the Astros either suddenly developed a team-wide sixth-sense at the plate or they started cheating, and the former seems incredibly unlikely.
The stats don't lie. It's only a matter of time before they get punished for their underhanded methods.