the raiders actually have a decent team. the early 2000s after the super bowl. they became a joke after awhile. their #1 draft picks in the mid 00's were busts. I think Al Davis took risks. he always took the players no one else wanted at the end of their career.
Al Davis was a major force in the creation of the AFL which I personally preferred over the NFL. Of course then the NFL and AFL merged.
But in the last several years I think the game of pro football passed Al Davis. He seemed to be actually holding back the Raiders.
In any case he will be remembered as a football legend. He had a major influence on pro football.