The secret to his success?
This is what "Catfish" told Gonzo about how he deals with the Sox:
“When they’re aggressive, (Perez) seems to know. He calls something off-speed. It’s just that kind of flow to the game that we’ve been able to have.”
That's called pitching backwards... start off over aggressive, 'home run or nothing,' mentally weak hitters with garbage and let them get themselves out.