The draft is about saving money by finding players who will contribute in their rookie contracts and save money compared to free agency (rent control Pioli calls it). Running backs are available on the open market for cheap. So, a RB in the first three rounds doesn't save much in his rookie contract. A team saves a lot more if the hit is on a defensive players in the first three rounds, especially DT's and EDGE rushers. For me, it therefore makes sense that Stevenson was drafted in the fourth, and that we took defensive front seven players in the 2nd and 3rd.