Johnson, 23, wound up going undrafted out of Penn State this year. He was among the rookies to try out for the Steelers during their rookie minicamp and later signed a contract with the team a month ago.
During his senior year at PSU, Johnson ran for 23 yards on four carries (5.8 YPC) and no touchdowns. Johnson mainly contributed as a special teams player.
Powell, 22, signed on with the Steelers as an undrafted free agent out of Coloarado a few months ago. However, he unfortunately lasted just over a week in Pittsburgh before he was cut loose.
During his four-year college career, Powell ran for 2,040 yards on 461 carries (4.4 YPC) to go along with 33 receptions for 229 yards receiving and 18 total touchdowns.