The Houston Astros have been egregiously stealing signs for the past three seasons, and the proof can be found all over the internet.
There has been footage shown of the (not so) elaborate setup in the Astros clubhouse in which a team employee or player would watch a screen and monitor it until they cracked the opposing team’s sign. Then they’d go full Carlos Gomez on a conveniently placed trash can, pummeling the poor bin loudly enough for the noise to be heard at the plate, as well as through the audio of the broadcast. And that was just the beginning.
This not-so-subtle smoking gun has led to a trail of crumbs for tireless investigators to comb through to find each and every instance in which signs were stolen and relayed to hitters.
Robert Arthur of Baseball Prospectus has been at the forefront of those searching through the evidence and he was able to pull an audio fingerprint from the televised Astros games. The audio he was able to isolate was that of the trash can banging, and confirmed that it was being used in correlation with the opposing pitcher’s arsenal, including a couple of Rays games.
Following the 2017 season or perhaps even during their 2017 postseason run that saw them become the World Series champions, the Astros adopted different methods of stealing signs that have yet to be determined.
One thing is for sure, however: the Astros offense improved significantly after the first recorded instance of sign-stealing was caught... you know, almost as if knowing what pitch is coming will improve your chances at the plate.
In his research, Arthur designated May 19th as the possible start of the Astros’ transgressions, but as he notes, it’s possible they were stealing signs before but just relaying their findings in a different capacity.
But it’s never good to just take someone’s word for it, so I took a look to see if there were improvements on offense once sign stealing was observed. For arguments sake, we’ll designate May 19th as the official start.
Looking back on the 2017 season and using a minimum of 100 plate appearances, both before and after that date, there is a significant difference for several members of the Astros roster.
Now, bear in mind, the Astros were already a fantastic offensive team prior to the May 19th designation as they held a 114 wRC+ which was good for the second highest in baseball.
Following May 19th, the Astros offense surged with a 124 wRC+ which was easily the highest mark in baseball, with the Cleveland Indians trailing behind at 110 wRC+ in second. It should be noted that the Astros offense wasn’t just successful at home, as they held a slightly higher wRC+ away from Minute Maid Park during the same time frame, and some believe the Astros were only stealing signs at home.
As a team, the Astros strikeout percentage dropped by one point following the noted sign-stealing, and their walk rate improved, but just barely. They still offered at the same percentage of pitches, swinging 45.3% of the time, which is right in line with the league average. But by looking at individuals we can see clear instances in where their performances improved following May 19th.
Carlos Beltran, who is believed to be one of the architects of the Astros sign-stealing initiative, increased his swing percentage by two points using the May 19th divide, and his contact rate went from 76.3% to 83.2%. George Springer also saw a sizable shift in his offerings, as he dropped his swing rate by nearly two percent and increased his contact rate from 74.2% to 80.3%. The biggest change of all, however, belongs to Yuli Gurriel, who dropped his swing rate by 7.6% and improved his contact percentage by 6.2%.
Was this the result of stealing signs, or just many players making adjustments? The timing may be purely coincidental, but the evidence is there to make case.
Now for the question at hand: if sign stealing happened, did this actually improve their performance? In other words, is improvement measurable for the season in which sign stealing was supposedly implemented?
The answer is a clear and definitive yes.
Across the board, almost all of the Astros hitters who had at least 100 plate appearances before and after May 19th saw substantial increase in their offensive output. Yuli Gurriel, who was noted above, had significantly changed his approach at the plate, saw his wRC+ go from 95 to 126.
Jose Altuve, who already was enjoying a fantastic start to the season, jumped from 141 to 166 on his way to becoming the American League’s Most Valuable Player.
Alex Bregman shook off some early season jitters to perform well above league average with a 40 point increase in his offensive production, while George Springer and Carlos Correa also seen tremendous boost in production.
There is much more research to be done and evidence to be uncovered, as this is likely just the tip of the iceberg of the MLB investigation into the Houston Astros — as well as every other organization in the game as sign-stealing becomes the next 2% or whatever.
But it certainly seems like the 2017 World Series Champions have been caught.