The outfield was "ankle-deep" in water and the dugouts were filled with feet of it.
The walk-through magnometers will be added to Nationals Park gates in accordance with a request from Major League Baseball.
Brewers shortstop Jean Segura, whose 9-month-old son died suddenly last week, received support from the Nationals and their fans.
One expert believes that continuing delay could hurt the value of any potential deal.
After months of silence despite requests for comment, a member of the team's ownership group finally address the rejected roof proposal.
Former Nationals starter Jason Marquis returns to the Nationals Park mound for the first time since leaving the club in 2011.
An expert estimated naming-rights deal would bring $10 million to $15 million a year for 20 years or more.