ALAMEDA -- Fatigue is a factor over the course of an NFL season, although it's tough to get a coach to admit it.

The Raiders' Dennis Allen has referred to his defense as "worn down" after each of the last two games, most recently after a 37-27 loss to the New York Jets.

With the 10-3 Kansas City Chiefs coming to O.co Coliseum on Sunday, Allen has altered the practice schedule in hopes of the defense getting its legs back.

"We've changed things up a little bit," Allen said after practice Thursday. "Hopefully that gives them a little bit of a boost."

The Raiders (4-9) have won just one of their last five games but have collapsed defensively in the second half of consecutive losses to Tennessee, Dallas and the Jets.

Against the Titans, it came in form of an 80-yard, 14-play drive to win the game. The Cowboys and Jets ran the ball effectively in the second half. Missed tackles were frequent.

Over the last three games, the Raiders have communicated less on defense and paid for it, giving up 24 of 44 (54.5 percent) on third-down conversions.

"It's a marathon, not a sprint, and when you're in the middle of a marathon, you're thinking about something crazy," defensive coordinator Jason Tarver said. "You've got to make sure the collective mindset comes back and gets back to where you want it to be."

Other than the Tennessee game, the Raiders defense hasn't been on the field for an inordinate amount in terms of time of possession or snaps.

Three defensive nonstarters -- cornerback D.J. Hayden, safety Usama Young and linebacker Kaluka Maiava -- are now on injured reserve. Defensive end Jason Hunter was lost for two games with a foot injury, just in time for Vance Walker to be out with a concussion.

Veteran players such as defensive end Lamarr Houston, cornerbacks Tracy Porter and Mike Jenkins, safety Charles Woodson and middle linebacker Nick Roach are rarely off the field. Roach, in fact, hasn't missed a snap this season.

The Raiders' blitzing tactics are creating less pressure, with only 11 sacks in the past six games after getting 21 in the first seven.

"I think it's the natural attrition of the season," Allen said. "Our guys have been in a lot of close games, a lot of battles. It's not just a physical thing, it's a mental thing. When you grind that hard to dig yourself out of a hole it takes its toll. We've done some things to freshen them up, and hopefully they'll be ready to fly around on Sunday."

Practices are being run at something approximating a walk-through pace, with emphasis on communication and assignments.

"Any defensive guy that plays this game, at this point they're going to be worn down, they're going to be tired, and the coaches are doing their part to freshen guys up a little bit," Porter said.

Houston, who had what he called his worst game against the Cowboys but played better against the Jets, said: "We're in Week 15, we've been taking a lot of banging and that's just how this game goes. As coaches they're doing a good job knowing when to pull back."

Film cut-ups have stressed the communication and energy level on good plays and bad. On the good plays, Tarver said, defenders are alert, they are talking, pointing and moving into position.

"Good defenses fly around and communicate and notice things, and you can just see the energy," Tarver said.

If the Raiders are sagging defensively, Chiefs coach Andy Reid wasn't going to confirm it in a conference call with Bay Area reporters.

"The way they're executing the defense has been better than the first time we played them, and we punted the first five times we had the ball," Reid said. "I think they're very good, and we're preparing for a good defense."

SUNDAY'S GAME
Kansas City (10-3) at Raiders (4-9), 1:05 p.m. CBS