NFL Week 8 betting lessons: Starting with Packers game, oddsmakers won't keep overvaluing Chiefs

It's rare that any trend lasts in the NFL. Oddsmakers are not going to let smart players beat them week after week. If there's a team that is overvalued or undervalued, odds adjust quickly. There's too much money on the line in NFL betting for the house to be slow to react.

The Kansas City Chiefs were a rare exception. That is finally changing too.

Since last Nov. 1, the Chiefs are 3-15-1 against the spread. On one of the league's most popular teams, there was an 83% winning trend by simply betting against them on the spread. It lasted a full year. That's rare.

Then Monday night happened. The Chiefs, who rose to 10.5-point favorites at BetMGM by kickoff vs. the New York Giants, barely won straight up. There was no time in which they looked like they were going to cover. It happened in a prime-time game and the talk of the NFL afterward was the 4-4 Chiefs' general malaise this season.

And books adjusted. On Sunday, the Green Bay Packers opened as 3-point underdogs at Kansas City for their Week 9 matchup. After the Chiefs' poor outing on Monday night and the reaction afterward, the Packers went back up as 1-point favorites. That's a 4-point swing based not on a Chiefs injury, but one performance on Monday night. That doesn't happen a lot.

Maybe the market will permanently adjust to the notion that the Chiefs have not been the team we remember from 2019. If the line move in the Packers game is an indication the oddsmakers are ready to shift their rating on the Chiefs in a significant way, bettors will have to adjust too. For those who have been making money fading one of the NFL's marquee teams for a year, one of the rare long-term successful betting trends in football could be ending.

Don't automatically fade backup quarterbacks

Whenever we see that a team will be without its quarterback, we assume they can't compete. Sometimes a team does look awful with their backup. But many times there's at least a one-week bump when the rest of the team focuses and plays well.

We saw backups play well on Sunday, and their teams play great around them. Mike White led the New York Jets to a straight-up win over the Cincinnati Bengals, who were 10.5-point favorites. Cooper Rush led the Dallas Cowboys to a win, after the Minnesota Vikings swelled to a 4.5-point favorite by kickoff. In-game bettors might have jumped on the Tampa Bay Buccaneers when Jameis Winston went down for the New Orleans Saints, but Trevor Siemian led the Saints to an upset win. Geno Smith helped the Seattle Seahawks to a 31-7 win despite oddly being just 3.5-point home favorites against an awful Jacksonville Jaguars team.

A similar tale could be told for the Green Bay Packers, who were without Davante Adams, other receivers and their defensive coordinator, and won despite the point spread moving from +3.5 to +6.5 for their game against the Arizona Cardinals.

It's a good reminder that teams often rally when they lose a key player, especially a quarterback. That might not last for weeks, but in the first game, there's often value betting on that team instead of against them.

Favorites, home teams have another losing week

In two Week 8 games, the favorite changed through the week. And the new favorites, the Indianapolis Colts and Vikings, both lost. Both were home teams. That shouldn't be a surprise by now.

It was a 6-9 week for favorites, and for home teams too. That continues the season-long trend of underdogs covering and home-field advantage not meaning much. Road teams are 63-59 straight up and 67-54-1 against the spread according to Covers.com. Underdogs are a pretty remarkable 68-53-1 against the spread.