KANSAS CITY, Mo. -- It speaks to all that is new in the Kansas City Chiefs secondary that many of the defensive backs approached safety Ron Parker this week for help in learning their responsibilities on defensive calls.

Parker signed with the Chiefs on Sunday.

The Chiefs have a lot of defensive backs who, in Parker's words, are "trying to figure this thing out." Of Kansas City's 10 defensive backs, four have arrived in the past month and three in the past week. Three are rookies. Counting Parker as new, the Chiefs have seven defensive backs who've joined in the past six months.

So Parker, by virtue of spending the past four seasons as a starter for the Chiefs, qualifies as a tutor even though he was released by Kansas City last winter and spent training camp and the preseason with the Atlanta Falcons before being cut again.

"From the time I walked in, the guys have been asking questions and it seems like they're trying to figure it out," Parker said. "They're trying to get it right now and there's no time to wait."

The Chiefs can't afford to wait any longer for their secondary to come together. The regular season begins Sunday against the Chargers in Los Angeles.

The Chiefs have won eight consecutive games against the Chargers because they've defended against quarterback Philip Rivers so well. Rivers in those eight games has thrown 13 interceptions with six touchdown passes. His passer rating is a feeble 66.

Since then, the Chiefs have traded their No. 1 cornerback, Marcus Peters, who had four of the six interceptions against Rivers over the past four seasons.

The Chiefs also might be playing without either of the safeties who were starters when training camp began. Dan Sorensen is out with multiple leg injuries. Eric Berry missed practice yet again Wednesday because of what the Chiefs are calling a sore heel, raising questions about his availability for Sunday.

"When I'm playing with Eric, I can just look over there [to communicate]," Parker said. "I don't have to say [anything]. We just make eye contact and we just know what each other is doing. With other guys, we have to communicate more, of course, because we haven't spent as much time being on the field together."

Parker is likely to start against the Chargers whether Berry plays or not. At least he knows his way around. Three of the defensive backs who figure to play a lot Sunday -- cornerbacks Kendall Fuller, Orlando Scandrick and Tremon Smith -- will be playing for the Chiefs for the first time. Smith is a sixth-round draft pick. Four members of the Kansas City secondary have played against Rivers as members of the Chiefs.

"This secondary is solid," Rivers said. "They've had some change. You're not really sure what's going to be what and where they're going to be, but it's still a talented group."

"I know there's been some negativity [about the Chiefs from the preseason], but I'm watching the tape and knowing the players and what that roster is about and what that coaching staff is about, and we know what Kansas City we're going to get on Sunday."

The Chiefs were dismal defensively in the preseason. Their starters allowed at least one touchdown pass to each of three backup quarterbacks. They might have been saved further embarrassment in the fourth game, when they didn't play.

Since then, they've released their third cornerback, David Amerson.

"We're rolling a lot of people in," coach Andy Reid said. "We're just trying to find what we can get away with on the defensive side, see who we've got and what they do best. Some of these are new faces. ... You've got [to have] an idea and find out what you've got and how to use them and what their strengths are and try to play to their strengths."

No matter their personnel, the Chiefs have been successful at getting Rivers off his game. He threw three interceptions in each game against the Chiefs last season, accounting for six of the 10 interceptions he threw all season.

For that, Rivers gave credit to the Chiefs and defensive coordinator Bob Sutton but said, "It's also been a lack of what we've done in the sense we haven't taken care of the football. It starts with me."