The Raiders' problem is clear: They've been drafting terribly
ESPN posted this infographic about the Raiders and their recent first round picks, and it shows exactly why they've been struggling the way they are.
Since losing a Super Bowl after the 2002 season, they've never won more than 8 games in a season, and they've averaged just under 5 wins per season.
This is due in large part to them completely wasting first round draft picks.
The Raiders have been fascinated with speedy wide receivers, but they completely passed on future Hall of Famer Larry Fitzgerald in 2004, instead going with Robert Gallery. The next year, they chose Fabian Washington, instead of Aaron Rodgers.
If they had gone with Ridgers, they could have gone with Calvin Johnsin in 2007, which could theoretically have landed them Fitzgerald, Rodgers AND Johnson. Of course, their draft position might have been different if they had gone with Rodgers and Fitzgerald in the prior years, but it's quite clear that the Raiders have been essentially flushing their draft picks down the toilet.
When they finally learn how to draft properly, they could be a force to reckon with. Until then, they'll just be the Raiders that we all know and (don't really) love.