If you May 20 in the pool for when the Nationals would need a sixth starting pitcher, collect now. Zach Duke will take the mound tonight against Ryan Vogelsong in a meeting of starters with ERAs of 8.40 and 8.06. The Nationals are hoping for five competitive innings from Duke, and Craig Stammen, the Nationals’ other long man, will be at the ready. The Nationals are trying to snap a two-game skid. Talk about the game right here.