Adrian Peterson remains unsigned. However, I think he deserves another shot in the NFL even at the age of 36. And last year, he averaged over 4 yards per carrying.
Another important thing I would like to note is that he is close with Najee Harris and having him on the team with him would be good for Najee's development over his rookie year. I think the two could end up being an explosive tandem.
The Steelers struggled on third and fourth down. Although, I would mostly place that blame on the offensive line play. They just weren't opening up the holes. This season they seemed to have addressed the position in the draft and free agency.
Point is, I think that Adrian Peterson would be great in those 3rd and short, 4th and short, and goal-line situations. He's still got a little gas left in the tank, and I think that the Steelers would be smart to give him and his agent a call.
It has to come down to his asking price. If it's for less than $3,000,000 I would say it would be worth it. If it's anything more, I would say to perhaps just roll with what we have. However, I think that Adrian would look good in the black and gold.