Desmond, who tied a career high with five hits Monday in the Nationals' 7-2 win over the Rockies, also was Washington's winner of the award in 2010, 2011 and 2013.
As the season draws to a close, a winner from the pool of 30 players -- one from each Major League team -- will be selected. Red Sox second baseman Dustin Pedroia won the award last season.
The final winner will be announced at the 15th Annual Legends for Youth Dinner in New York City on November 18.
To learn more about the MLBPAA, visit www.baseballalumni.com.
Nick Kosmider is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.