Gio Gonzalez walked into the Oakland Athletics' clubhouse in August 2008 and immediately began breaking every one of baseball's unwritten rules, starting with the chapter on How a Rookie Must Behave. In the clubhouse, he committed the unpardonable sin of placing his personal iPod on the communal speaker dock. On the field, he fumed at every borderline ball-strike call, berated himself over walks and threw things in the dugout. "I sat him down," said A's lefty Dallas Braden, himself just a second-year player at the time, "and explained what was going to happen if this kept up — and it wasn't going to be pretty. I had to give him some tough love and tell him to cool it for awhile." By now, Gonzalez, a 26-year-old native of Hialeah, Fla., has matured into a force — a solid clubhouse citizen, a 2011 all-star and one of the best young left-handers in the game. But now, Gonzalez is also long gone from Oakland — having been the cornerstone of a six-player trade in December that brought the Nationals the front-line starting pitcher they craved, and that cost the A's a pitcher who had become beloved by teammates and coaches alike.