For the fourth straight season, the Washington Nationals have traded for a big-name reliever in the middle of the season. Trades in previous years for Sean Doolittle and Ryan Madson, Mark Melancon, and Jonathan Papelbon were made because the Nationals were missing a set closer. This time, however, the Nationals are adding to an already strong bullpen.
The Nationals bullpen pre-Herrera this season is already first in the NL in fewest walks per nine innings, third in WHIP, and fifth in xFIP.
Herrera will only strengthen these numbers as he has the third-best BB/9 in all of baseball at 0.