If I recall correctly, this is based on passer rating differential. Which as Kevin mentions, is an extremely good stat for predicting success. In most years, a team in the top 5 in PRD wins the Super Bowl, often the #1 team. I think it's a much better metric than the gut feelings these lists are usually based on.
The Chiefs may be lower than they should be because Mahomes has had an uncharacteristically bad TD:INT ratio this year. They’ll likely move up as the season goes on.
The Packers position is maybe higher than it should be because Malik Willis has had very clean games (passer rating of 130) when Love has missed time. Love's high INT # is offset by throwing a lot of TDs too.
The numbers don't really care about our personal opinions though.
But now that I say all of that I'm thinking maybe it isn't PRD? It looks like the Packers' PRD is only +1.7 while the Lions are +6.6, so these numbers don't match the list (or I'm doing the math wrong). Kevin, are you using a different stat? Spill the beans!