When the Alliance of American Football came to a sudden close, NFL teams swooped in to scoop up a great number of them. I believe over 100 players or so were signed to 90-man rosters, and the Pittsburgh Steelers were as active as any team in bringing them in, including some who they might have already been familiar with.
Those whom they signed from AAF teams were J.C. Hassenauer, Jack Tocho, Kameron Kelly, JT Jones, Winston Craig, Casey Sayles, and Greg Gilmore. The latter two had been in training camp and the preseason with the team a year ago.