Cover Photo: Harry How/Getty Images

Week 15 proved that there's no such thing as a sure thing when it comes to betting on NFL games.

The MGM Mirage took two massive bets, on heavy favorites, netting the sportsbook around $1 million, thanks to two big-time upsets.

The Seattle Seahawks were favored by close to a touchdown over the San Fransisco 49ers, putting their moneyline around -200. The Philadelphia Eagles were record-setting underdogs taking on the Los Angeles Rams on Sunday night.

The wagers on the favorites were pretty massive. Half a million dollars on the Seahawks moneyline, and a $180,000 moneyline bet on the Rams at -900 odds. It hasn't been made public if the wager on the Seahawks was to win $500,000 or was risking that amount, but either way, that's a lot of money. The Rams' bettor would have netted $20,000 had LA won.

But, alas, the underdogs were both victorious. The 49ers' 26-23 upset win over the Seahawks was MGM's largest win on a single NFL game this season. And the Eagles' 30-23 win netted them almost $250,000.

The Philadelphia victory was the sixth double-digit underdog to win outright this season. That only happened four times in 2017 and just once in 2016, so to say wagering on these longshots is trending positively for bettors is a bit of an understatement. But if you have the funds to take these heavy favorites, good for you.

Seeing this happen as often as it has, one has to wonder, is the risk worth the reward?

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