Sign stealing in baseball is a tradition as old as the game itself, dating back to the 19th century. In the modern game, how signs are stolen can often spark confrontation.

In the fifth inning of the Cubs' 7-0 win over the D-backs, jawing between dugouts broke out as Arizona suspected Chicago third-base coach Quintin Berry was stealing and relaying signs from the coaches’ box. D-backs starter Merrill Kelly and his allies suspected Berry was picking up his changeup grip from the open angle of his glove.

The two teams fighting for postseason positioning in the National League began jawing back at each other from their respective dugouts, with Arizona bench coach Jeff Banister and Chicago’s Ryan Flaherty at the center of it all. Both sides started shouting at each other while waving their fingers in distaste.

Berry appeared not to have left the third-base box, a rule implemented this season by MLB as a way to divert from coaches stealing signs. Coaches are not permitted to leave the box, which is a two-foot-long area designated by a half-rectangle once a pitcher is on the rubber. 

“Stealing signs is as old as baseball,” Kelly said postgame. “... I think if it’s a guy on second base and they see the grip in your glove, or if the hitters can see something that you’re doing with your glove, I think that’s fair game.”

Kelly and Berry chirped back and forth at each other once the pitcher exited the game for reliever Taylor Clarke. The Cubs went on to tag Kelly for three earned runs and win the series opener.