The catch Cubs shortstop Starlin Castro made Tuesday — a play on which he sprinted into left-center field to reach Alejandro De Aza's no-man's-land pop-up, only to have it bounce out of his glove before he bare-handed it for the out — is why you don't trade this guy. Well, that and his ability to hit almost any major-league pitch hard. And this: For a guy who has yet to play a game of consequence in nearly 2½ seasons in the big leagues, look what happens when the local stakes are raised.