THE OPTIMISM related to the Raiders' upcoming season can be attributed to the vastly improved secondary, the gifted young quarterback and the heralded rookie running back.

Though destructive factors lurking near the surface could undo everything, the upgrades provide a more competitive roster.

So it's unfair that much of what happens will rest on the shoulders of a man yet to prove he's a starter.

Production from new additions DeAngelo Hall, Gibril Wilson, Darren McFadden and Javon Walker are essential to success. The same for returning members JaMarcus Russell, Tommy Kelly, Derrick Burgess, Kirk Morrison and Thomas Howard.

None, though, is more essential than Terdell Sands.

If Big T can play at the level the Raiders are paying him to meet, the defense will be better than at any time since the Super Bowl season. Good enough to keep the Raiders in games, even win a few.

Anything less, the scenes in 2008 will be similar to those of 2007 — only with a different cast. Opposing runners will pile up season highs, and the expensive secondary will be wasted.

By swapping Fabian Washington and Stuart Schweigert for Hall and Wilson, the Raiders have assembled arguably their strongest secondary since returning to Oakland in 1995. Nnamdi Asomugha and Hall are fabulous corners, Michael Huff seems suited to free safety, and Wilson is a high-velocity strong safety.

Given this, opponents who dare to pass must be very careful. Or foolish. Why challenge a terrific secondary if you can sprint through a holey run defense?

Which shines the light on Sands. The massive (6-foot-7, 335 pounds) nose tackle was effective against the run as a part-timer in 2006, received a four-year, $17 million deal in the offseason and responded by disappearing.

He was overweight, distracted and ineffective. He played his way onto the bench, then into the doghouse.

Seven months later, Sands offers no denials. He said after a training camp workout Thursday that he takes "all" the responsibility for Oakland's porous run defense. He was given a specific assignment and not only flunked but didn't give his best effort.

"I thought I was," he said. "But when I watched film, it really wasn't like I was the year before. So I take personal responsibility and put it on myself."

There were mitigating circumstances. Sands' mother died in the offseason. Insofar as he barely knew his father, Sands had lost his rock.

"You lose anything like that, some things take tolls on you," he said. "You lose things that are aspects of life right there."

A tangle of emotions and understandably blue, Sands fell behind in conditioning, backed away from cardiovascular workouts and found comfort in eating. His weight went up, approaching 400 pounds, his production went down.

"That's behind me," he said. "I've got to push on this year."

Having seen his backslide — and backside — Sands claims new commitment. He changed his diet, worked out more consistently. He opened camp well enough, passing the mandatory conditioning drill, with teammates urging him on.

With Kelly projected at one tackle, Oakland's success on defense requires Sands be good enough to start, to focus on suffocating the run game. That would free up Gerard Warren to play both tackle spots.

The idea is to force opponents to throw, which plays into the strength of the roster. It allows Wilson to back off the line, lets Morrison and Howard roam, unleashes Burgess, gives Asomugha and Hall opportunities to make plays.

Realizing Sands' significance in the grand scheme, coach Lane Kiffin sees a lineman attempting to redeem himself.

"His weight is down; it's as low as it has been since I have been here, but not as low as it was two years ago," Kiffin said. "He has a good bounce to his step, and he's practicing harder. He's focused on football. We need him to play, and we need him to help because he's a dominant run player at times, and if we could get him to do that at a consistent level, then it would be an exciting thing."

Moreover, it would be the last thing opposing offenses want to see.

Contact Monte Poole at mpoole@bayareanewsgroup.com.