Why Has the Bengals-Chiefs Spread Moved So Much?

After the Cincinnati Bengals' blowout victory over the Buffalo Bills, a number of football fans on social media had the same question:

Why did the Bengals open as a 1.5-point road underdog in Sunday's AFC Championship against the Chiefs, only for that line to move so substantially in the Bengals' favor —  to Cincinnati -2.5 at some shops early in the week?

And now, why has that number moved back to Chiefs -1 overnight on Wednesday into Thursday morning?

The answer, as you probably would assume, is largely the status of Patrick Mahomes. But the way in which Mahomes' injury has affected the line is interesting — and it's not the only reason.

Let's rewind a few weeks. The Bengals had been +2.5 at home during these two teams' matchup in December. Home field advantage in the NFL is worth approximately 1.5 to two extra points, PointsBet trader Mike Korn told the Action Network on Tuesday. That means the Chiefs would have been favored by roughly 6.5 points on December 6th if that game were in Kansas City.

Yet six weeks later, the Chiefs are playing the Bengals at home, opened as just 1.5 point favorites, and were at one point 2.5-point home underdogs.

Was that significant change in theoretical odds within a six-week period due to Patrick Mahomes' high-ankle sprain, or were the Bengals finally earning some respect from oddsmakers after Joe Burrow's fifth career postseason victory?

Caesars' Assistant Director of Trading, Adam Pullen, believed Mahomes' injury is the biggest factor in the change in odds, stating that his ailment is worth roughly four points to the line.

"When you take away a quarterback of his caliber and his ability to play at 100%, it drastically changes the game plan," Pullen said. "He's not going to be making some of the throws. He can't plant on that foot. Maybe things will change during the week, but, historically, this is a four- to six-week injury."

Pullen indicated Mahomes' injury was worth four points to the line earlier in the week when the Bengals were favored by one. The injury could impact Mahomes' spontaneous style of play; he did not throw a single pass outside of the pocket in the second half Sunday's game for the first time in his career, according to Next Gen Stats.

According to FOX Sports' injury and performance analyst Matt Provencher, Mahomes could "be down about 12 to 18% in overall offensive productivity, especially in quarterback rushing yards, and more of a limited potential to throw the long ball.”

And that all made sense — until Mahomes appeared at practice on Wednesday as a full participant, without a walking boot.

By Thursday morning, the Chiefs were back to one-point favorites, showing just how much of the line movement for this game is based on what we know (or don't know) about Mahomes' health.

Still, Mahomes' injury doesn't account for all of the discrepancy in the line from December to the AFC Championship Game. On that note, Pullen would not underestimate the way in which the Bengals won on Sunday and its impact on the line. Pullen says, "When you get to this point, it is not if you win, but how you win."

This postseason lends credence to Pullen's point. We've seen another example of the importance of how you win games on the other side of the bracket — Philadelphia's dominance of the Giants vis-a-vis the 49ers' relative struggles to beat the Cowboys. Prior to the Divisional Round matchups, Pullen figured Philadelphia would be favored by a point against the 49ers in a hypothetical NFC Championship. The Eagles are now favored by 2.5 points.

Similarly, Pullen believes the Bengals' blowout of the Bills in Buffalo accounted for at least a point to 1.5 points in value toward the Bengals — meaning it's as valuable to the line in comparison to Mahomes' injury at this juncture in the week, after his Wednesday appearance in practice.

According to DraftKings, oddsmakers may finally be recognizing Joe Burrow's dominance over Patrick Mahomes and the Chiefs, as well. Burrow improved to 3-0 against Kansas City on December 6th, and this latest win may have stamped a narrative that Burrow owns the Chiefs.

And, finally, there's the way that money has flowed in on the game. According to Action Network data, prior to Wednesday, 79% of the spread bets and 74% of the money had come in on the Bengals since the line was posted.

PointsBet told the Action Network on Tuesday that roughly 80% of their handle was on the Bengals ML and spread.

BetMGM provided a figure between 70 to 80%.