The latest conventional wisdom is that the Chiefs and the Chargers are much improved.
I like the Chiefs defense and Alex Smith may be a top game manager as a QB - so far lack of turnovers and a charged up D have gotten the Chiefs off to a good start. The Chiefs, however, do not have depth on the Defense that I can see and the offense is not dynamic. Get up early on this team and it will not be able to respond -it takes them completely out of their game. As good as some of the players in the defense are - they will not survive intact the entire season. IMO - the Chiefs are still a 500 team.
The Chargers have some talent and Mike McCoy seems to have done a good job so far. However, the Chargers have a wildly uneven starting talent base - so they can be exploited and as they get scouted during the season - they will be exploited more efficiently as the season progresses. They too have depth issues and wear and tear on the season will make them more vulnerable. I also see the Chargers are a marginal 500 team.
Meanwhile the Broncos roll with a crushing amount of top players out for various reasons and a favorable schedule in terms of travel and rest. I think the Broncos matchup better against the Chiefs than most teams - the Bronco's offense can go right at the Chiefs defense and stretch it to the breaking point -even with the Chiefs top players healthy. The Chiefs offense can not play catch up - game over.
The Chargers have a punchers chance to beat the Broncos, but those are long odds.