Ken Rosenthal and Evan Drellich of The Athletic report that MLB's investigation into sign-stealing by the Houston Astros in 2017 has now widened to include the Boston Red Sox's activity in 2018:
Three people who were with the Red Sox during their 108-win 2018 season told The Athletic that during that regular season, at least some players visited the video replay room during games to learn the sign sequence opponents were using. The replay room is just steps from the home dugout at Fenway Park, through the same doors that lead to the batting cage.