I love these stories and wonder how much is just in the pitchers head. If true why not use it against the hitter? Tip a slider and throw a fastball. Hitter would not have a chance.
I'm sure they try and do that, but it's the same thing as faking a tell in poker. You would first need to take the time to invest in creating the fake pattern, hustling with some intentional failure. Maybe do it in lower leverage situations and flip the script in higher leverage situations?
I'm just shocked gagne saw something from his couch that kimbrel, catchers and coaching staff couldn't pick up on for weeks. Kind of embarassing.