The hit and run play they mention in the article depends on the defense being unaware of the play. Basically, the batter will swing no matter the pitch, which l

The hit and run play they mention in the article depends on the defense being unaware of the play. Basically, the batter will swing no matter the pitch, which let's the runner on base start running before the ball leaves the pitcher's hand. If the pitcher and catcher know it's a hit and run, then they can pitch an unhittable ball and then throw the runner out. The Wikipedia page is pretty good if you want to know more. More abstractly, baseball has a few situations that only exist because a team can coordinate among themselves without revealing their plan to the opposing team. This leads to more mixed strategies where a greater variety of plays are enacted with some probability. Without signs, those plays wouldn't work, and the game would become more boring. IMO I think speeding up the game will make it more exciting, and they will figure out how to signal in the time available. Besides this coordination, signals are also used to give instructions to individuals. E.g. base stealing or bunting. However, since these plays don't require coordination among multiple players, these could be spontaneously performed at the player's discretion in the absence of signals. This could actually make a more exciting game as players exhibit more agency and create more chaos.