Admitting to a mistake is always hard, especially when you’re stubborn by nature, and the mistake in question is also a sizable investment.

They’ll never admit it publicly, but that’s what the Cardinals’ relationship with Kevin Kolb has come to just four months into a six-year marriage. They’re already at the point when one partner is sleeping on the couch, and the other may be looking for a better quarterback, and it’s statistically proven that most divorces are the product of one partner finding a better quarterback.

Kent Somers of the Arizona Republic reports that Kolb won’t be cut this offseason, an option that’s available to the Cardinals if they refuse to pay his $7 million roster bonus. Somers’ report shouldn’t be greeted with surprise since the Cardinals gave up Dominique-Rodgers Cromartie and a second-round pick for Kolb in their trade with Philadelphia, and then signed an unproven backup to a six-year contract worth $63 million, $21 million of which is guaranteed.

The result of the trade and contract was Kolb being designated the new franchise quarterback, so walking away from that commitment is more than just an admission of failure. It would be the Cardinals’ front office saying that we screwed up, and we exercised poor judgment of talent that led to a mismanagement of our financial resources. To err is human, but to publicly acknowledge such a massive error is rare.

The Cards paid Kolb too much, too soon, but that monetary value is set now, and those dollars dictate that giving a 27-year-old one more year to grow and demonstrate he can handle being a starter is currently the best course of action. But without a vast and nearly immediate improvement next fall, admitting their mistake before the losses mount is the only wise option with a player who’s paid and viewed as a star player, but isn’t remotely playing like one.

Both Bill Belichick and Brad Childress pulled that same trigger with Randy Moss last year, and the Redskins had a similar situation with Donovan McNabb. Washingtan gave a clearly aging and struggling quarterback a five-year extension worth $78 million, but that number meant little. The contract only guaranteed McNabb $3.5 million, allowing the Redskins to cut the veteran prior to this season without any further financial obligation. They chose to trade McNabb and let him languish in Minnesota instead, but the option to jettison him free of charge remained.

The difference between McNabb and Kolb is of course their age, and the guaranteed money, with that $21 million looming and motivating Arizona to be patient. But on the field, there are some similarities between the Kolb we’ve seen this year, and the McNabb we saw before he was released by the Vikings. That’s beyond scary. It’s horrifying.

In his six game appearances, McNabb had a passer rating of 82.9. Kolb’s missed seven games due to injuries, and in his eight starts (technically nine, but he threw one pass before leaving with an injury in Week 14) he has a rating of 81.1. Kolb’s completion percentage is 57.7, while McNabb’s was 60.3, and Kolb has been sacked 30 times to McNabb’s 16. Kolb’s sack numbers can be partly blamed on a poor offensive line, but that’s not a sufficient excuse for averaging nearly one sack per game more than a washed up 35-year-old.

Tebowmania has made me despise the quarterback “wins” statistic, but eventually when a team is consistently winning with one arm under center and not the other, a trend has to be acknowledged. John Skelton isn’t the answer in Arizona either, but the Cardinals have won four of their last five games and seven games overall, and only two of those wins have come during Kolb’s starts.

Skelton’s made $3,139.53 per completion this year, while Kolb’s made $86,301.37. The NFL isn’t much different from any other business in that mistakes hurt the bottom line, and Kolb has to start erasing his red ink quickly in 2012.