Williams suffered a hamstring injury last week at Arizona. He played in 11 games, mostly in a special teams’ role. He had six tackles on defense and nine on special teams with one fumble recovery.
Brown signed a two-year deal. He was four of five on field goal attempts this season for San Diego and has made 77 percent of his kicks for his career with Pittsburgh, Houston and San Diego.
It might not be the only roster move the Cowboys make today. The Cowboys could call up quarterback Chris Greisen from the practice squad with Jon Kitna unlikely to play Sunday at Philadelphia because of a left oblique strain.