, the apparent promise of starting a backup quarterback -- that a diamond in the rough will rise to heroic status when given an opportunity -- usually proves to be a mirage. More often than not, the dream comes to a crashing halt. After all, most backups are backups for a reason. But what happens when a team with serious playoff hopes finds itself relying on the understudy under center?That's the situation facing the and . The 8-1 have the NFL's best record, but they'll have to go the rest of the way with , as veteran starter with a torn ACL. The , meanwhile, will attempt to stay in the fight for the NFC East behind castoff .Before we delve into Stanton and Sanchez, let's consider how backup quarterbacks have performed thus far this season. It's been a mixed bag, to say the least. was 1-4 in his five starts for the -- and though it is technically credited to Cousins, was secured after he was replaced by , who rallied the troops to come back against the in Week 7. completed 70 percent of his pa ses for 230 yards and two touchdowns in for the . had an awful completion rate of 54.5 percent and threw more picks than touchdown pa ses in for the . , who began Joe Carter Jersey the year as the ' third-string quarterback, has a respectable 3-5 mark as a starter, but nothing about him screams long-term fixture. And while Stanton did win in Palmer's stead earlier this year, we should note that when he gave the job back to Palmer heading into Week 6, the had the 29th-ranked overall offense. Here are my takes on Stanton and Sanchez going forward, with one facet of the game emerging as especially crucial for both quarterbacks:Drew Stanton, Arizona CardinalsStanton already has two wins under his belt this season from a three-game stretch that Palmer mi sed with a nerve i sue. In Week 2, , in Week 3 -- his one lo s was in Week 5. That's a cro s-country road win, a win against a team that was a favorite in the NFC West and a relatively close lo s -- the didn't truly pull away until -- to what many believed to be the best team in football. Of course, now that Palmer is done for the season, Stanton's job has really just begun.Stanton's 2014 stat line is hardly impre sive; he's completed le s than 50 percent of his throws with just three touchdowns on 93 total attempts. In his two complete games this season, he averaged just 205.5 pa sing yards, slightly better than his lifetime average of 172.3 as a starter. While that is hardly anything to cheer about, one bright thing stands out: Stanton has yet to commit a turnover this season. And a quarterback who takes care of the ball always gives you a chance, particularly when you're a team with a defense playing the way it has been. When a backup is under center, it's OK for drives to end in kicks -- even a po se sion that results in a punt can be a good one. Just don't turn the ball over.Consider what the did after on the first drive of the fourth quarter in . Facing a four-point deficit, Stanton completed an 11-yard pa s, scrambled for 4 yards, threw for another 26, then connected with for that gave Arizona the lead. The Cards' defense then picked off Davis twice in a row, , before forcing a fumble that was . Obviously, a team can't plan to clinch games with multiple defensive touchdowns, but a team can most certainly limit its mistakes and hit big plays when opportunities present themselves.This isn't limited to Stanton. The quarterbacks I mentioned in the introduction have a combined record of 7-11. In their seven wins, they combined for a total of just four turnovers; in their 11 lo ses, they combined to turn the ball over 20 times. Seems pretty simple to me.Mark Sanchez, Philadelphia EaglesWith while he recovers from a broken collarbone, Sanchez will get his first start under . And while Sanchez, who made 62 starts with the , is certainly a known commodity, he is still the backup quarterback. experts might lead you to believe Sanchez is the answer to all your problems, but real life is different from : You lose a lot more than two points when you throw an interception in the NFL. And Sanchez has certainly done his fair share of that. In two of his four seasons as the ' starter, he threw more interceptions than touchdowns, and his career touchdown-to-interception ratio is 70:71. I know what you're saying: The two picks he threw in relief of Foles weren't his fault. The first one was tipped by a receiver; as for the second, you could argue didn't turn fast enough for the hot read. Still, a turnover is a turnover. Regardle s of who's at fault, turnovers damage the team's cause and make it harder for the quarterback to win, a problem that is magnified when a backup is slinging the pigskin. The bottom line is, if the and want to keep rolling, it won't be enough to just win the turnover battle; they'll have to live by it. If they avoid making mistakes and stick to the formula, both squads can make the playoffs behind their backups, particularly with the head start they have. That said, in today's NFL, you need more than a game manager to win in the postseason. Are these teams capable of making a run? Yes. But are they likely to? Not exactly. Follow Brian Billick on Twitter . Yonder Alonso Jersey