As with many struggling franchises, the Raiders' downfall over the past six seasons has been hard to define in a sentence or two.

The running game has been at times tepid, at times formidable. The pass rush has been occasionally strong, often nonexistent. The locker-room vibe has spiraled into near-chaos at certain points, but has more often been surprisingly solid.

There has been one constant, though: shabby run defense.

As the team followed up a Super Bowl campaign in 2002 with a 4-12 finish in 2003, the rushing defense came unglued. The Raiders ranked dead last in the NFL in yards allowed on the ground in '02, giving up 156.9 yards per game.

Al Davis hired Rob Ryan as defensive coordinator in 2004. And while Ryan had his successes in Oakland, his run defense got worse every year " 125.8 yards per game in 2004 (22nd in the league), 128.1 yards in 2005 (25th), 134 yards in 2006 (25th), 145.9 yards in 2007 (31st) and 159.7 yards last year (31st again).

Now the Raiders are banking on Ryan being the problem.

In essence, the team did almost nothing to upgrade its anti-run personnel over the offseason. The Raiders drafted four defensive players, but three of them " Matt Shaughnessy, Slade Norris and Stryker Sulak " are primarily edge rushers. Only safety Mike Mitchell is a potential run-plugger, and he will go into training camp as the No. 2 strong safety.

The man currently running ahead of Mitchell, second-year safety Tyvon Branch, also is a physical presence. But remember, so was the man Branch replaces, Gibril Wilson. Wilson was a liability against the pass, but was one of Oakland's best tacklers last season. The Raiders did sign one interior defender, Ryan Boschetti, but he would look to be the team's fourth defensive tackle at best.

If the Raiders are to get any stouter against the run in 2009, massive DT Terdell Sands will have to play much better (and stay on the field more) than he did a year ago. And new defensive coordinator John Marshall will have to significantly change his players' assignments.

Or their mentality.

That seemed to be the message Ricky Brown " who is moving from outside linebacker to the middle (backing up Kirk Morrison) this year " delivered to reporters after practice Wednesday.

"For me, always stopping the run is a little bit about attitude," Brown said. "It's kind of something that's deep within a guy."

Let's hope he's right. Because it will largely be the same 11 guys looking deep within themselves this year.