Nats prospects Elijah Green and Cristhian Vaquero have struggled. They know it.

Elijah Green and Cristhian Vaquero know they have struggled. The stats for the 20-year-old, power-hitting Green: a .208 batting average with a .649 OPS. More than 44 percent of his plate appearances have ended in a strikeout. And for Vaquero, a switch-hitting 20-year-old: a .190 batting average …