It's not a lie if you believe it: Why players promise SB wins

Another NFL player guaranteed a Super Bowl victory Friday - against the New England Patriots, of all teams.

Related - Jeffery affirms SB guarantee: 'We're bringing that trophy back to Philly'

Every time an athlete like Alshon Jeffery makes one of these guarantees, fans are puzzled.

Why would you give the other team bulletin-board material? Why would you set yourself up for embarrassment? What is there to gain?

Here are three reasons why football players guarantee victories in one of the most difficult contests in sports:

Irritation

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Two weeks of intense media coverage can really weigh on a coach or athlete.

A team like the Philadelphia Eagles has not only been repeatedly reminded they're not favored to win the Super Bowl, but they've also been dealing with nearly two months of people assuming their season ended when Carson Wentz's season ended.

For Jeffery - who, after being part of the Chicago Bears' franchise-worst season, guaranteed a Super Bowl win last year - listening to everyone count out his team likely irritated him enough for him to say something he might regret.

Potential fame

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The most renowned Super Bowl guarantee in NFL history belongs to "Broadway" Joe Namath, who called the New York Jets' upset win over the Baltimore Colts three days before Super Bowl III.

Namath's guarantee was special for three reasons: 1) he was the first to do it, 2) his team was a 17-point underdog, and 3) the Jets actually won.

Guaranteeing an upset win and following through could make a player somewhat of a legend, but few other successful big-game predictors, including Plaxico Burress in 2008 and Shannon Sharpe in 1999, garnered the same level of notoriety for their confidence as Namath did.

Overconfidence

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If you believe things can be spoken into existence, you almost need to publicly guarantee a win. But in the case of NFL players, it's more likely they just have an absurd amount of confidence.

Given the extremely low odds of making it from high school to the college level to the pros and then to the Super Bowl, NFL players develop extreme self-confidence just by being part of the 1.6 percent.

When asked questions about how they could win, it must be tough not to snuff out the doubt when they're already planning the celebration party.

In the words of George Costanza, it's not a lie if you believe it.