It's definitely not a matter of desire. This is a man who fought his way from undrafted afterthought to franchise quarterback. He's the football version of a gym rat, constantly seeking an advantage by studying film and working on intricate details of his game. He's doing everything he can to give himself a chance to win the kind of games that will be remembered for generations.
"At some point," Romo says, "you're either good enough or you're not."
Unfortunately for Romo, whose team faces the New York Giants with the NFC East title and a playoff bid at stake Sunday night, that isn't necessarily true.
Just look at the most recent Giants-Cowboys game for evidence. Romo's 321-yard, four-touchdown, no-pick performance wasn't good enough to prevent a 37-34 loss Dec. 11 at Cowboys Stadium.
According to Pro-Football-Reference.com, there had been 71 previous quarterback performances since 1960 that featured at least 300 passing yards, four touchdowns and a passer rating of 140.0. Those quarterbacks played on the winning team on all 71 occasions.
Romo became the lone exception. Quarterbacks who put up those eye-popping stats are now 71-1.
Yet some people pointed to Romo's possibly overthrowing receiver Miles Austin by a foot as proof that Romo wilted under pressure. (Austin admitted he made a poor adjustment to a catchable pass on the key play with the Cowboys clinging to a late lead, but never let the facts get in the way of a good "Romo choked" angle.)
Forget about being good enough. Almost perfect wasn't enough that night.
If Romo is good, the Cowboys probably will be playoff spectators for the second consecutive season. Romo has to be great for the Cowboys to feel good about their chances to beat the Giants -- and certainly to do any damage if they reach the postseason.
The Cowboys are relying on Romo more than ever. They need him to be spectacular to overcome a defense that has appeared overmatched against quality foes since Rob Ryan's early-season smoke-and-mirrors effect wore off. (See the Giants' 510 total yards Dec. 11.) They need him to make up for mistakes by a spotty offensive line and mask an inconsistent running game that has lacked depth since rookie DeMarco Murray's season-ending fractured ankle.
Romo, whose bruised throwing hand suffered last week isn't considered a major concern by the Cowboys, has responded with arguably the best season of his career. He didn't receive an invitation to his fourth Pro Bowl, but he has a career-best 102.2 passer rating despite playing several weeks with a fractured rib, throwing for 3,895 yards with 29 touchdowns and only nine interceptions entering the NFC East title game.
Since then, however, only Green Bay's Aaron Rodgers, New Orleans' Drew Brees and New England's Tom Brady have played quarterback as well as Romo. He has a 22-4 touchdown-interception ratio since his three-pick disaster of a second half against Detroit.
Romo has been ridiculously effective since a pain-killing injection for his ribs stopped being part of his pregame routine. He has completed 68.2 percent of his passes for 1,936 yards and 19 touchdowns with only two picks in those seven games, plus the one painful series in last week's loss against the Eagles.
Add four game-winning drives to Romo's résumé this season and it's obvious he's the primary reason this team has a chance to claim the NFC's final playoff spot.
Romo routinely has been among the best quarterbacks in the NFL this season. He can only hope that's good enough to beat the Giants this time.
Tim MacMahon covers the Cowboys for ESPNDallas.com.