A.J. Pierzynski Defends Cubs Coach in Diamondbacks Sign-Stealing Dispute

What Happened The Diamondbacks accused Cubs third-base coach Quintin Berry of relaying pitcher Merrill Kelly's pitch types to hitters during a recent game, sparking a heated dugout confrontation that pulled in players and coaches from both sides. Arizona was convinced Berry had picked up a tell on Kelly's changeup and was signaling it to lefty hitters. MLB reviewed the situation and ruled Berry did nothing illegal.

Ex-MLB catcher A.J. Pierzynski weighed in with a blunt take: as long as a coach stays inside the third-base coach's box, they can move, wiggle, clap, or gesture however they want. "He would wiggle his left hand on change-ups or whatever it is. That's not illegal. When has that ever been illegal?" Pierzynski said. "As long as you're in the coach's box, you can do whatever you can do."

Why the Rule Is So Murky Here's the part that trips people up: sign stealing itself isn't banned in baseball. It never has been. Coaches and players are allowed to steal signs the old-fashioned way — with their eyes, their instincts, and film study of tendencies. What crossed the line in MLB's infamous 2017-2019 scandals (looking at you, Astros) was using technology — cameras, monitors, electronic buzzers — to decode and relay signs in real time.

Quintin Berry wasn't accused of using a camera or an earpiece. He was accused of watching Merrill Kelly's glove closely enough to notice a pattern and then signaling that pattern to his own hitters with body language. That's legal. It's the same skill scouts and coaches have used for a century, just executed live from the coach's box instead of during video prep.

The Real Issue: It Still Feels Dirty Pierzynski didn't fully let the Cubs off the hook on principle, even while backing the legality. "I think it's a little bulls*** when it comes from a coach," he admitted, drawing a distinction between a hitter picking up signs on their own versus a coach doing the relaying work for them. That's the tension at the heart of this story — something can be completely within the rules and still rub players the wrong way.

Merrill Kelly's frustration wasn't really about the rulebook. It was about feeling like the Cubs found an edge he couldn't stop, short of changing his signs entirely. That's baseball's oldest cat-and-mouse game, and it's not going away just because MLB cleared Berry.

What to Watch Next Expect pitchers around the league to tighten up their sign sequences when Berry and the Cubs are in town. This kind of controversy tends to change behavior even without a rule change — teams start mixing signs more, using PitchCom more aggressively, or watching third-base coaches like hawks. The Diamondbacks may not have won the argument, but they've put every future opponent on notice that they're watching.