St. Joseph, Mo. ? Jon McGraw is back for his fifth season with the Kansas City Chiefs and 10th in the NFL. That qualifies him as the elder statesman of the secondary.

The defensive backfield may be one of the younger position groups at Arrowhead Stadium, but it’s also among the most talented. Lining up beside the 32-year-old McGraw is second-year safety Eric Berry, who is 10 years younger. They’re joined by 25-year-olds Brandon Carr and Brandon Flowers as legitimate shutdown cornerbacks.

That quartet is a big reason the Chiefs went from a 4-12 club two years ago to a 10-6 playoff team last season.

The Chiefs were a middle-of-the-pack defense last season, but that was largely because they struggled to get penetration up front. The backfield yielded fewer than 220 yards passing per game, a significant improvement over the previous year, and a big reason why Kansas City went from 30th in total defense in 2009 to 14th last season.

“We have guys back there who have been working hard,” Berry said. “We just want to keep working as a unit and keep that chemistry going. That’ll be a big plus.”

Berry, a former Tennessee star, made 72 tackles and four interceptions last season, returning one of them for a touchdown. It’s precisely that kind of playmaking ability that made the Chiefs select him fifth overall in the 2010 draft and put him into the starting lineup every game his rookie season.

“That last year had a lot to do with my growth, but at the same time there’s still more I can learn and more I can work on,” Berry said. “I learned a lot last year, but I still have a lot to learn.”

That became painfully evident in the first round of the playoffs, when the Raven’s Joe Flacco gouged the secondary for 265 yards passing and a pair of touchdowns. Baltimore coasted to a 30-7 victory, a demoralizing way to wrap up a season in which the Chiefs far exceeded expectations.

“It’s been a long, long offseason since our last wild card game,” Carr said.

Carr reportedly contemplated offers from several other teams after the Chiefs placed a first-round tender on him, but the cornerback from Div. II Grand Valley State signed last week. One of the big reasons is that he wanted to keep building a defense that has taken significant strides under coach Todd Haley.

Carr immediately resumed his place in the starting defense as soon as he was able to begin practicing.

“I feel good. This whole offseason I’ve been training, doing drills, trying to simulate game-type situations and get ready to get out here,” Carr said after practice Thursday night.