DeOssie was selected by the Dallas Cowboys in the fourth round (110th overall) of the 1984 NFL Draft, after dropping because he was selected by the New Jersey Generals in the first round (15th overall) of the 1984 USFL Draft. As a rookie, besides being the long snapper on punts, he was the backup linebacker behind rookie Eugene Lockhart. He had 8 defensive tackles. He was nicknamed "Barney Rubble" by his teammates. A couple years later they nicknamed him beach ball, because of the many shades of color his face would turn in the sun.