The Broncos and Manning are already known entities. The Broncos took the eventual champs to double OT and everyone knows Manning will keep them in pretty much every game. Hell, they looked terrible at times vs the Colts and still almost came back.
The Chiefs were 2-14 last year and all they have to go on is that they have a legit defense and their opponent win % is .328.
Pretty simple... the Chiefs will get their chances, so the 'no respect' thing is pretty pointless.