The Giants' Santiago Casilla had his first major league at bat against the Florida Marlins.
He managed a 4 pitch walk. But he certainly didn't look very comfortable in the box.
According to baseball-reference, Casilla had 14 minor league plate appearances in his career. In those appearances he drew 1 walk, had 6 hits, 3 doubles, a triple, 5 RBI, a stolen base and a single strike out. That's a career minor league batting line of .462/.500/.769.