You're committing Duffey to another inning in a game you trail, meaning he's done until at least Monday. Not to mention, as you noted, it's the middle innings. Somebody's gotta pitch the end of the game, too. Littel and Stashak are in the bullpen, they're gonna have to pitch in this series. Rocco made the right call. Duffey threw 20 high stress pitches. It was another pitcher's job to take over from there.