Mike,
There have always been qarterbacks who put up fantastic regular season statistics, but who can't get the job done in the playoffs, with the pressue of the season being on the line. Certain QB's manage to get the job done under playoff pressure and some don't. Take a look at Romo's numbers in elimination games and playoff games. I remember him choking against the Giants at home in the playoffs in 2007, throwing a pick to end the game. Then I remember him choking against the Giants in the last game of last season, a winner take all for the NFC East title. Ditto this year vs. the Red Skins (3 more picks, including one with 3 minutes left in the game to seal it for the Redskins).
I notice Philip Rivers is also on that list. He is another player that puts up fantastic regular season stats, but never seems to win the big game in the playoffs. Neither Eli Manning nor Troy Aikman, with 5 superbowl rings between them, is on that list. If I had to choose between Romo and Rivers as against Eli and Aikmen, I'd take Eli and Troy every time and twice on Sunday.
In 2008, on one of these threads, we did a breakdown of the great playoff quarterbacks, looking at the winning percentage and championships won of every quarterback who played in at least 10 playoff games. Several of them are on the list of most efficient quarterbacks, but a bunch of the greatest don't make the list, starting with Johnny Unitas, Terry Bradshaw, Bart Starr and Troy Aikman, all of whom have more championships and Superbowls than you can shake a stick at. Heck, Eli is 8-3 in the playoffs with two championships. I don't know how they calculate efficiency, but those are a lot of QB's I would feel more confident in than Romo or Rivers.
I agree that the Cowboys have a lousy offensive line, but the Giants had a lousy O-line last year (they were dead last in the league rushing the ball, and Eli got hit more than 20 times in the NFC Championship game against the 49ers) and they won the superbowl. This year Eli wasn't quite able to overcome the lousy offensive line play, in combination with the poor defense, but I have every confidence that with a revamped O-line and the addition of a quality cornerback, the Giants will be serious contenders next year because of Eli and his receiving corps. Do you have that confidence with Romo and the Cowboys?
Then again, it might not be Romo, a lot of commentators blame the Cowboys problems on Jerry Jones' interference with the head coach and insistence on acting as the GM. There is a lot of talk that the players can't be effectively coaached because they know the head coach doesn't really have the last word in whether they stay or go. Whatever the problem, be it the QB, the head coach or the owner, something needs to change before the Cowboys are real contenders like they were in the 1970's and the 1990's.