Several of those SB winning teams you mentioned had defenses that could apply pressure to the QB, force turnovers and make critical stops. NO won their SB by picking off Peyton Manning for a pick-six when the game was on the line. Both the Giants SB wins were aided by containing Tom Brady and the Pats high powered offense. Both the Steelers SB wins under Roethlisberger were aided by #1 defenses and forcing turnovers. The offenses of those SB winning teams leaned on the passing game which is why you can name those QBs with several being named SB MVP's. The Cowboys have never had a defense under Romo they can depend on to make critical stops and win games which has put a lot of pressure on him to have to carry the team. Not having a solid defense or a consistent running game is what led to those three straight 8-8 seasons. If you put too much on Romo to have to win games he presses like he did against Carolina and it leads to turnovers.
He had the most efficient season of his career last year due to having a solid running game that took pressure off him and the defense. Controlling the ball with the running game kept the defense off the field an average of 13 fewer plays than the previous season and it led to Romo having a career low in pass attempts. Romo can only carry the Cowboys so far before the floor caves in. He plays his best when he's not having to do too much. He knew how dependent the team is on him and he clearly pressed against Carolina which led to a miserable performance and the re-injuring of his shoulder. The Cowboys have never won a championship without an elite runner in their backfield. Romo needs a solid, consistent running game for him to be the best QB he can be.
Does the name "DeMarcus Ware" ring a bell?
The Cowboys were ranked #1 in sacks in 2008 and were perennial top ten from about 2006 to 2009 and in 2009 they had the #2 ranked defense in scoring. That same year they shut out their last two opponents to get into the playoffs and then held their first opponent, Philadelphia to 7 points until another garbage score late.
Of course, in the playoff game against the Vikings, it didn't help when Romo fumbled the ball three times and threw an INT to give the Vikings two drives that started in the Cowboys redzone. Nor did it help when the offense could only score a total of three points.
Tony Romo and the Cowboys had their opportunities and that whole "Tony didn't have this, Tony didn't have that" argument is totally unfounded.
Tony Romo cannot carry the Cowboys without help. The Cowboys win only 40% of the time he throws more than 35 passes and 75% of the time when he throws less.....meaning that Tony Romo requires a balanced offense to be successful....as do 95% of all QB's.
I'm not getting on Tony Romo, but I am far from deifying him. Anyway, this was about the running game, don't know what defenses had to do with it except that a defense's best friend is a successful running game.