DENVER — The Broncos were without their star pass-rusher and had a rookie quarterback making his debut and 19,094 fans unwilling to show up to watch a 3-8 team in 33-degree weather. They were also one loss away from ensuring a third consecutive losing season for the first time in 46 years.



Every number and every circumstance seemed to play against the Broncos when they took the field Sunday to host the Chargers. Yet somehow, Denver overcame its own miscues and did just enough not to let their fourth-quarter lead go to complete waste.



On a field goal in the final seconds, the Broncos defeated the Chargers 23-20 to complete a season sweep of their division rivals.



How?



Five reasons, really.



1. Lock made a change



The Broncos danced around the obvious for a week. Drew Lock, their second-round pick who had been on injured reserve with a thumb injury, was going to start. They knew it and everyone else did, but they refused to say...