Ingram's YPC in 2013 through 2015 was equal to or higher than Deuce's YPC from 2006-2008. Don't know how you can objectively conclude that Duece was a "special back" and Ingram is not.
There's something about the way Ingram runs that makes people think he's less successful than other backs, but his YPC says otherwise. It seems his running style doesn't get him many style points. Fortunately, style points don't matter.