Before I answer that question, I'm going to point out some things to you.
There are 18 Hall of Fame Quarterbacks who played in the Super Bowl era of the NFL. Half of them didn't win a Super Bowl.
There are 20 quarterbacks who have won a Super Bowl and are eligible for the Hall of Fame. Only 9 are actually in it.
Now, some of those 9 have won multiple Super Bowls. Bart Star was the first, who played with the Hall of Fame tandem Paul Hornung, Jim Taylor, some more Hall of Famers on defense, and arguably the greatest coach of all time, Vince Lombardi.
Then there was Terry Bradshaw, who had another great backfield in Franco Harris and Rocky Bleier. Oh, the Steel Curtain also helped him out, arguably the best defense of all time.
Then came Roger Staubach, who had another legendary coach in Tom Landry, and a Doomsday Defense of his own. The Cowboys teams of the 70's always had a great running game, including one lead by Tony Dorsett.
Next was Joe Montana. Those 49's teams had some great defenses, lead by Ronnie Lott, as well as a Hall of Fame coach in Bill Walsh, and some other guy named Jerry Rice.
After that was Troy Aikmen. He played with arguably the best offensive line of all time, and the NFL's all team leading rusher Emmitt Smith. The Cowboys defense in the early 90's was one of the best at that time.
John Elway waited 15 long years, but he was able to win 2 Superbowls in his final 2 seasons. In those '97 and '98 seasons, the Broncos defense was in the top 10 for turnovers forced and points allowed. Also in those '97 and '98 season, the Broncos were a top 5 rushing team.
Jim Plunkett isn't in the Hall of Fame, but he did win 2 Superbowls. If you combined the 1980 and '84 Raider's defenses (the years they won the Superbowl), they combined for 55 interceptions, including 64 sacks in the '84 season alone. They gave up an average of 18 points per game those two years, including 17 in the playoffs. Marcus Allen was also on that '84 Raiders team, if that helps.
So, is it safe to say that all the teams that had great success are great teams, not just had great quarterbacks?
In the past 5 seasons, there is this one NFL team that has rushed for an average of 108 yards per game, with 9 touchdowns per season, on average. If those were applied to this season, their rankings in comparison the rest of the NFL would be 19 and 25, respectively. Their defense over that time gave up an average of 22.5 points per game, and forced an average of 17 turnovers per season. That scoring defense this year would be 18th in the NFL, and the turnovers would be 30th. This team has gone 42-38 in that time, with one playoff appearance. So basically, they are a below average team, right?
Now, you're probably wondering about quarterback play, right? Before I get to that, consider that Tom Brady plays on a team that leads the NFL in rushing touchdowns, is 5th in points allowed, and has forced 41 turnovers, best in the AFC. Peyton Manning is on a team that is in the top 5 for just about every major defensive category. Aaron Rodgers plays on a team that is 11th in yards and points allowed, and that same defense has recorded 47 sacks, second in the NFL. And those are the 3 best quarterbacks, right? Who all play for great teams?
Back to that average team, what would you say is the reason they have played bad? The quarterback? What quarterback could do well on an average team? So far, the only great quarterbacks in the playoffs this year are on great teams.
So I'll finally explain that the average team I showed is the Dallas Cowboys. While Tony Romo doesn't always play great, many are asking him to do things that not even the best quarterbacks in the NFL can overcome, which is an average team. I showed earlier how the great teams are ones that are great across the board. It's common sense really, the great teams are great teams. A quarterback can simply be the missing piece. Petyon Manning moving to Denver as an example. Their defense played great down the stretch last season, had a solid offensive line and some good, young receivers. Throw in Manning, and that offense becomes spectacular, and a great overall team.
Before I fully make my point, I'll give you a quick psychology lesson. There is this thing called "conditional learning". You may recall Pavlov's dog, where this earned its fame. In conditional learning, you learn certain behaviors from a repetitive action. In Pavlov's experiment, he would ring a bell near his dog and give him some food. After doing this many times, Pavlov stopped giving his dog food, but would still ring the bell. Despite the absence of food, the dog's mouth would still salivate at the sound of the bell, in anticipation of the food.
To show how this applies, imagine that the sound of a bell is a Cowboy loss. The food is the reasons why they lost, and the salivation is the blame going to Romo. Years ago, many people gave different reasons, but it would eventually go back to Romo. Now, whenever the Cowboys loose, it's almost instinctive to blame Romo. Very little blame goes to the rest of the team, regardless of their own individual performances. Many fans and analysts show this thinking, saying it's all on Romo.
So, who's to say the other Cowboys players haven't adopted that mindset too? Is it possible that the players think, whether they realize it or not, that if they loose they will not be held accountable? No one in the media will blame them, so they don't worry about it. Many of the players show little to no effort on a good number of plays, and don't seem too worried when things don't go their way.
Now I"m no psychologist, but it is possible. It doesn't matter if it is Romo's fault or not, a team simply cannot think that, and there is a good chance they think so. The sad part is Romo is willing to take all of the blame. I'm not saying to let him get away with loosing, but whenever you loose, no one played good enough. It gets to a point where too much is being asked of one player, and not enough of the others. Until he is actually lining up on defense, Romo can not help them. He can give words of encouragement and kicks in the butt, but none of that matters until the other players do the necessary work themselves.
Yes, the Cowboys have gone 1-6 in their last 7 win-or-go-home games, that is well documented. But, did you know in those 6 losses, they've given up an average of 30 points? Before you say that a great quarterback would have been able to overcome those defensive meltdowns, you should also know that in games where the opposing team scored 30+ points, Drew Brees, Peyton Manning, Tom Brady, and Aaron Rodgers this year have a combined record of 2-16. One of those wins was against Buffalo, so take that however you want. If those guys can't overcome bad defensive play, who can?
(Sorry if all these statistics bore you, that's just how I back up my arguments)
I won't say what should happen to Romo, but I will say the success of a team is more dependent on each player focusing on their own job, and worry less about others. If I focus 100% on what I'm doing, I can play perfect. Once I worry more about the other players job, I am less focused on my job and am more likely to screw up. (I'm talking in a football sense, just to clarify).
A quarterback can have the biggest individual impact on a team, but he's far from the majority.