The evidence is damning.
According to a report from Evan Drellich and Ken Rosenthal of The Athletic, the Houston Astros have used hidden video cameras to aid in decoding signs and relaying what pitches are coming when their offense is at the plate. The alleged abuses took place during the 2017 season, with former Astro Mike Fiers going on the record (along with other unnamed sources) to detail the process which some Houston hitters employed to gain an advantage over opposing pitchers.
Sign stealing in baseball is nothing new. Opposing baserunners have been trying to pick up the catcher’s signals and relay them to their teammates at the plate for over a century.