They OBVIOUSLY do happen. If your team weren't lousy they wouldn't have a 5-9 record. You don't play the same opponent every week. Those 4 DIFFERENT decent teams can have an off week, and your team just happens to be the lucky recipient of those bad weeks. Which they have been. The Raiders suck, and you know it. They ARE a lousy team, and are not better than their record (unless you can prove they are). It's up to you decide whether the teams they beat are not that good........and the Chiefs aren't, so that's actually only 4 fluke wins.
And yes, they have beaten the Broncos at home 2 years in a row. How many times have the Broncos won against the Raiders since 1995? 76% of the time.
And two of those times were in the Black Hole in the past 2 years and 6 of the last 7 years..........what's your point, we've had mediocre teams in the past few years ourselves. Thank god they haven't been as bad as the Raiders.