Mike Clay from over at Pro Football Focus posted a study discussing how predictive statistics for a rookie running back are for the remainder of their career. The study takes a look at historical data from running backs classified into three categories, based on their rookie yards per carry average. Then, a closer look is taken at how their careers continued after being in that initial rookie category.
For me to try to summarize the study seems unnecessary -- it'd be much clearer if you read the article to understand all of the data yourself. With that said, the conclusion that the author arrived at for the future production of Cleveland Browns running back Trent Richardson was not the most promising:
This study also shows that we should be pessimistic about Trent Richardson’s chances of developing into a stud. Of all backs selected in the first two rounds since 2008, none with a sub 3.9 rookie-season YPC have exploded into an elite player. In fact, many have struggled. Richardson is in a category with Ingram, Moreno, Spiller, Vereen, Thomas, Brown, Best, and Mendenhall. Fellow 2013 rookies Vick Ballard and Ronnie Hillman also fit the bill.
The study does not take receiving statistics into account. A lot of those "non-stud backs" compared to Richardson don't possess anywhere near the receiving ability that Richardson does.
You can also scan the rest of the tables in the study to find sub-grades for other or former Browns running backs, including Chris Ogbonnaya, Chris Jennings, James Davis, and Armond Smith. Montario Hardesty was not eligible for the list because he did not carry the ball once as a rookie (due to injury), which was a requirement for the study.
Meanwhile, our expectations for Richardson in 2013 remain high.