Has a World Baseball Classic game ever ended 4-0?
It has. 4-0 has been a World Baseball Classic final 2 times in 270 games. The first was Japan beat China on March 5, 2009; the latest was Panama beat Brazil on October 4, 2022.
That makes 4-0 the 41st most common final score out of 87 that have ever occurred in World Baseball Classic. One point away, 5-0 has happened 5 times and 4-1 has happened 12 times.