Has a World Baseball Classic game ever ended 1-0?
Yes. World Baseball Classic has seen a final score of 1-0 3 times. It first happened on March 9, 2009, when South Korea beat Japan, and most recently on September 23, 2016, when Israel beat Brazil.
That makes 1-0 the 27th most common final score out of 87 that have ever occurred in World Baseball Classic. One point away, 2-0 has happened 6 times and 1-1 has happened never.