 Downs was signed as an undrafted free agent by the Dallas Cowboys after the 1981 NFL Draft.He wasn't selected because he suffered a pinched nerve in his shoulder as a senior, which affected his play and earned him a reputation for not being aggressive.He was so impressive in training camp, that he became the third rookie in Cowboys history to begin the season as a starter, after free safety Randy Hughes suffered a dislocated right shoulder and Dextor Clinkscale an Achilles injury in pre-season.