I notice that only one other reigning Superbowl winner from the previous year was an underdog in the Superbowl the following year. In Superbowl 12 the Dallas Cowboys beat the Denver Broncos 27-10 and yet in Superbowl 13, the Dallas Cowboys were + 3 1/2 dogs (Some say it opened Dallas + 2 1/2) to the Steelers.
Pittsburgh won that game 35-31. The infamous Black Sunday game where the books took it in their keisters.
Odds-makers knew from which direction they would get hammered when they posted this opening number. Getting hit with a wave of KC money did not surprise them.
Does being an underdog work for this year's Chiefs? They are the reigning champions and yet they are an underdog? Will the 49ers unseat the reigning champion Chiefs this year?
https://www.betfirm.com/point-spreads-for-every-super-bowl/