...A couple things:
1. Murray averaged 4.7 last season. McFadden averaged 4.6 this season. Randle averaged 4.1 this season. Just so we're oriented in this discussion.
2. The .1 difference overall between Murray and McFadden isn't significant in and of itself.
3. The .5 difference between McFadden and Randle IS significant.
4. Randle trended downwards with more carries. It was true in 2015 and has been true his whole career. You can argue against it all you want, but it's reality.
5. There is such a thing as putting too much emphasis on YPC for running backs. It's a useful statistic but it doesn't always tell the whole story.
6. Consistent forward progress for a running back is a big deal. Example: Back A has 50 yards on 10 carries. Carry 1 went 50 yards. Carries 2-10 each went for zero yards. Back B has 40 yards on 10 carries. Every single carry went for 4 yards. Give me back B, without hesitation.
7. Randle was not giving consistent forward progress. He would have a few good runs and a vast majority of bad, less than 2 yard runs. Every game. Every running back doesn't do that, and it's not even typical.
8. No one said, that I've seen, that Murray got 5 yards on every carry. What you can say about Murray is he gave us consistent forward progress. To a lesser extent, so did McFadden. Randle didn't.
9. You can't say that the running game wouldn't have made a difference this season and therefore it isn't important, and think you have a point. Nobody is saying that the difference between 4-12 and 12-4 is a better running back. You need to have a QB and good coaching first and foremost. This season's problems were many. The way we used the running game the first 6 or so weeks was only one of them.
10. That said, the difference in the running game can certainly make a difference between 8-8 and 12-4. And it's not only the talent at the position, but also how the coaches use it.
It would be foolhardy to go into 2016 without solidifying and planning to use the running game. If we have a healthy Romo it absolutely can make or break the season.