As far as professional football is concerned, the closest thing to to this I can recall (but far less egregious) was players admitting to betting on their OWN teams. Their penalty was a one-year suspension.
Having watched most of the first half of the Raiders vs. Redskins game in question here, it occurred to me at the time that the Raiders' offensive performance was dreadful, especially considering that they were believed to have a potent and explosive offense which had scored 45 points the prior week. I know they were shut out in that first half and had very few first downs.
Other sports have shown zero tolerance of players who deliberately gave less than their best. The NFL, if wants to be on the level and is concerned about the basic integrity of its game on the field, must do a complete investigation of this Raiders-Redskins game, including thorough study of the game film. And anyone found taking a dive - regardless of the "reason" - should be banned from the league for life. Any thing less would be condoning consumer fraud.
BTW, were any suspicions along these lines reported by the MSM?