I think all the references to Polian saying T-Rich was a stud is a bit unfair. Most people thought T-Rich was going to be good, its a clear reminder that nobody knows exactly how these players are going to turn out.
That being said i don't think it's a secret that there is no comparison at all between T-Rich and Barkley. Fournette, Elliot and Gurley were all can't miss top tier running backs, but Barkley could be the best of the group, possibly the best since AP.
I personally think if he drops to 3 we get lucky and would be stupid to pass on the pick, but i think the most likely scenario is either the Giants take him, or someone trades in to the top 2 for him. Leaving the Colts in a trade back situation to grab extra picks and hopefully Chubb or Nelson with a later pick.