Pittsburgh had to bring in some center help after they lost Maurkice Pouncey to a serious ankle injury during last weekends game.
Legursky, 29, originally signed on with the Steelers as an undrafted free agent out of Marshall back in 2008. He spent five years in Pittsburgh before joining the Bills as a free agent in 2013.
Last year, Legursky signed a contract with the Chargers and appeared in two games before he was placed on season-ending injured reserve.
He hadn’t found any reported interest since free agency opened several months before this.
Nelson, 28, originally signed on with the Buffalo Bills as an undrafted free agent out of Florida back in 2010. He spent three years in Buffalo before he signed on with the Browns as an unrestricted free agent in April of 2013.
Nelson most recently played for the Jets, but was released in October of last year. The Steelers signed him to a contract a few weeks ago.
In 2014, Nelson appeared in six games and caught eight passes for 65 yards receiving.