If you go after Petersen you will pass on the draft for RBs.
Which would be a huge mistake.
Whoever Dallas finds in FA will be a downgrade from Murray (even Murray himself). The team could have used a dynamic #2 last year, and that still hasn't changed either. Barring incredible luck in free agency and/or Joseph Randle's development, the gap is going to have to come from the draft.
Denver's experience with all their RBs just proves you can't go wrong going for quality and depth at the position.
Bottom line is Dallas can't squander Romo's window by just hoping a niche FA or two and Joseph Randle's improvement will replace Murray's outstanding 2014 production and playmaking ability. This has to be a full court press.