FFI had an interesting point when it came to team defenses. They said usually teams that stop the run put up alot of fantasy points because their opponents have to pass more often. In the Raiders case, their run defense was horrible (and Im not sure it has improved much this year). That should keep the Raiders fantasy defense more low scoring than it should be.
The run defense wasn't horrible, it just wilted under the pressure of constant attack. Their passing ranking is skewed because teams didn't need to pass, they were constantly protecting a lead, and there was really no reason to throw the ball vs. the Raiders, there was no need to take the extra risk. So the passing ranking is puffed up because of that. But the rush D ranking doesn't tell the entire stoy either. They weren't as bad against the run as their ranking suggested, teams were conastantly handing the ball off, and after 3 and outs, or worse, by their offense
every series, it takes its toll.
The Raiders have a problem with the inside run, more than anything, but the emergence of Terdell Sands last year hopefully will preclude the use of Tommy Kelly and Sapp side-by-side.
As to the D improving or not, with Kirk Morrison, Sam Williams, Thomas Howard, Michael Huff all coming off their first years as starters at their respective position, I think improvement is almost a given. This was a very young defense last year, right down the middle. Aside from Sapp, every player on thie D last year is on the ascent.