Robinson, serving as the potential winning run, was picked off first base in the bottom of the ninth inning Thursday night to end Chicago's 2-1 win over the Nationals.
"I'm always looking for that," Rizzo said. "He's just getting off big there, and he's the tying run, so he's getting a big, aggressive secondary lead. Rossy gave me a look and confirmed the sign and made a good throw."
Robinson wasn't alone. Cubs manager Joe Maddon didn't see it coming either.
"I had no clue," Maddon said. "Like on many occasions, I had no clue.
"You give them freedom to declare to be a baseball player. I don't want to be that control freak that has control every play that is put on a baseball field. Then if you do that, you're players don't play."
Had the play ended differently, and Ross' throw was not right on target -- though he said he never thought of that possibility -- Maddon still would've been a fan of the decision.
"I love it. Absolutely love it," Maddon said. "If he actually had thrown the ball down the right-field corner, I would've been fine. I would've been absolutely fine with the whole play because it was the right thing to do."
The play left former Silver Slugger winner Anthony Rendon, who was already 2-for-4 in his first game back from the disabled list in 2015, standing at the plate and Michael Taylor, the tying run, at second base.
"I got too far -- ballgame. It's pretty much plain and simple," Robinson said. "It's frustrating. That's on me. That can't happen. I took the bat out of Anthony's hands. He is one of our better hitters. That's just on me. That can't happen. I really can't explain it. I wasn't really trying to go anywhere. I just couldn't get back fast enough."