The low point might have been a 44-6 loss to the Philadelphia Eagles in the 2008 regular-season finale, one of the worst collapses in franchise history.
But the beginning of the fall can be traced back to Dec. 7, 2008, at Pittsburgh. Romo was intercepted three times that day. DeShea Townsend returned one pick 25 yards for the decisive score in the fourth quarter of a 20-13 loss to the Steelers at Heinz Field.
Romo will see the Steelers for the first time since that game Sunday at Cowboys Stadium with a playoff spot hanging in the balance. But he is not that December quarterback anymore, even if many don't want to recognize the change.
So much of the discussion regarding Romo is about what he hasn't done or can't do that the narrative differs from the actual facts.
Let's look at one: Romo is terrible in the fourth quarter. In reality, Romo has the NFL's highest fourth-quarter passer rating in league history at 102.6.This season his passer rating in the final quarter is 105.1, which is fourth best in the league behind Jay Cutler, Aaron Rodgers and Peyton Manning.
And maybe it's time to remove the December and January narrative, too. In the 11 December or January games Romo has started and finished since the 2008 season finale at Philadelphia, he has been nothing short of terrific. Excluding last year's December loss to Philadelphia in which he came out after the first series with a bruised hand, Romo has thrown 22 touchdown passes and just four interceptions. He has seven multi-touchdown games and no multi-interception games. He has five 300-yard passing games to go with 299-, 286- and 289-yard efforts.
His lowest passing total in the 11-game run is 249 yards against San Diego. He has completed 69 percent of his passes.
But the Cowboys are only 6-5 in those games, and that's the rub. It doesn't matter if four of the five losses have been by seven points or fewer and that one came in overtime.
"It's about winning and losing," Romo said last week and has repeated over and over again in recent years.
The Cowboys are 2-0 in December for the first time with Romo as the starter and for the first time overall since 2001. Romo had a career-high 150.5 passer rating two weeks ago against Philadelphia while completing 22 of 27 passes for 303 yards and three touchdowns. Last week at Cincinnati, he had a low passer rating of 74.6, but he completed 11 of 15 passes for 128 yards and a touchdown in the fourth quarter and directed the game-winning drive in the final minute.
"He's on top of everything he has to do," wide receiver Miles Austin said.
Romo has to be for the Cowboys to continue this current run.
DeMarco Murray's return from a sprained left foot has helped return balance to the offense. Dez Bryant is delivering big plays as he continues his ascension toward becoming one of the NFL's best receivers. Jason Witten's third-down dependability has kept drives alive.
But Romo is the difference-maker, just like Tom Brady in New England, the Mannings in Denver and New York and Aaron Rodgers in Green Bay.
"We're 4-1, I think, in our last five, and we need to end up at 7-1 in our last eight," Romo said. "We know this game is as big as last week. ... It's been like that for a while. As the season keeps going, we keep putting our head down and going to work. We continue to have some injury issues that have not been, obviously, beneficial to us, but guys have stepped up and we're having to find different ways to win football games.
"I told some of the guys, if we can just keep these games close, we can win it in the fourth quarter and we can do some things. And we've been able to do that, I don't know, four or five times this year, and that's sometimes the way you have to play games."