While cornerback was widely considered as a primary concern for the Steelers coming into the draft, Kevin Colbert didn't address the position until the third round.
Cameron Sutton wasn't one of the premier talents at the position in this draft class, but he was one of the most unknown prospects because of his combine performance and lack of exciting stats. What he did have on his side was four years as a starting cornerback in the SEC.
Sutton became a team captain alongside Derek Barnett, partially because he could play cornerback at any spot on the field. He specialized in covering the slot receiver but could proficiently run with receivers outside the numbers as well.
The Steelers most definitely took note of that and thought he would be a good addition to their secondary and possibly an answer to their woes when they try to switch to man coverage.