I looked it up...not public or city property. Private parking. So they had to have permission of the ownership or some judge’s order.
Just a humble guess...they were set to browse the concession area and probably take down 50-percent of the work-force there.
Maybe just have marked ICE vehicles on the public streets at the entrance and exists every home game. I wonder what that would do to their attendance and concession sales in the stadium?
They could probably find a few thousand just in the stands watching the game