The Nationals selected Herz to their 40-man roster Tuesday.
Herz was acquired from the Cubs this past July as part of the Jeimer Candelario trade and is now protected from being plucked away from another organization in next month's Rule 5 Draft. The 22-year-old left-hander holds a career 3.64 ERA with a whopping 413 strikeouts in 281.2 total minor-league innings.