Well football is a team sport so all 22 players on Offense and Defense need to do well for the team to succeed...as well as the guys on special teams.
Running backs do matter, even though the league is more pass first oriented. Yet I am always a strong believer that it all starts in the trenches. If you have a good offensive line, you are going to be able to do a lot offensively. Running backs do not do very well when there are no holes to run through, and they look like crap when DT's and DE's are hitting them in the backfield because your RT and guard are turn styles. You give a running back a 4 yard hole every play and you don't need a QB. Same applies for a QB...you give a QB 4 to 5 seconds in a clean pocket and he is going to slice up your secondary.