The Chargers are not at the level they were last season. But they still are a level higher than Denver. The Chargers' record shows 4-7, but they have outscored their opponents on the season. The Broncos, by comparison, have a minus 42 scoring differential.
LA has surrounded Philip Rivers with an excellent cast of skill position weapons. The Broncos can't match that firepower. They have serious QB problems. The Chargers' defense gets back star safety Derwin James this week. He had been out the entire season. In their last game, the Chargers held Patrick Mahomes under six yards a throw, the lowest of his career. 
The Chargers are off their bye facing a must-win spot here. The Broncos are a demoralized bunch with chemistry issues surrounding first-year head man Vic Fangio.