Park in Buzzard Point on Second Street SW as close as you can get to Q Street on the 12-hour meters. Pay for the whole day until 6:30 PM (I use the Parkmobile app to avoid having to carry loads of change). Then retrieve the car after the game.
The reason for parking as close to Q Street as you can is that Second Street is one-way southbound south of there and the soccer stadium construction has closed off all the cross streets, so unless you want to risk going the wrong way on a one-way street when you leave, you'd have to loop all the way down past the marina. After Springsteen it was a mess getting out of that area even with lots of people illegally driving on the wrong side of two-way streets and going the wrong way on one-way streets. Hence parking as close to the two-way part of Second Street as possible.
I've parked back there for ballpark events since 2010 and this past Thursday's Springsteen show was the only time I ever had any sort of problem. I will admit that there have been times late at night where if we did not leave the ballpark very promptly we felt somewhat uncomfortable walking through the neighborhood across South Capitol Street there. (Right after a game there are loads of people and no issues, but there have been two times when an older black lady was yelling profanities at passing white people about tromping through her neighborhood.) This didn't used to be a big deal because we'd just walk down to Potomac Avenue and across via R Street to Second Street, but R Street is now fenced off between First and Second for the soccer construction, so you have to walk through the residential area.
