CARSON, Calif. -- David Boston was one of the marquee signings of the offseason, but the boldest moves by any team came in the Chargers defense. Fast legs on offense. Young legs on defense. If it works, the Chargers are recharged.

Second-year coach Marty Schottenheimer felt he had no choice. Opposing quarterbacks exploited the Chargers lack of speed on defense for a league worst 268.4 yards a game and 26 touchdown passes, turning a 7-3 start into an 8-8 finish. The consequences were drastic because the Chargers had to say goodbye to longtime defensive leaders Junior Seau and Rodney Harrison.

"We had to get more speed back there," Schottenheimer said. "We ended up finishing 32nd on pass defense and a lack of speed was a large part of that. It was because we weren't fast enough back there. The only way to get that done is to bring in some younger guys who can run."

Watching the Re-Chargers practice in the Home Depot Center offers optimism. Drew Brees, in his second year as starting quarterback, is making better decisions and releasing the ball quicker, but finding open receivers isn't as easy. Young legs are scurrying to the ball. Second-round pick Drayton Florence, a corner in a safety's body, explodes toward a receiver with remarkable closing speed. Backup strong safety Hanik Milligan chases down receivers and knocks balls out of their hand. Quentin Jammer, last year's first-round pick, looks smooth and relentless running alongside a receiver.

Physically, this is a fast group. If they can come together as a defensive unit in camp, the Chargers could get off to their typical fast start and be able to sustain it. Ryan McNeil, a longtime NFL corner converting to safety, surveyed the Kiddie Corps with a simple observation, "These guys can play." Which is why Schottenheimer and general manager A.J. Smith are looking forward to the exhibition games like a youngster on Christmas Eve.

"I think we will be okay," Jammer said. "The experience is not there, but the talent is. It's tough. There is so much competition because there are so many people back there who can play."

The Chargers drafted four rookies for their secondary. Florence is playing behind Jammer at left corner and first-rounder Sammy Davis is behind Tay Cody on the right side. The Chargers have already gone on record as saying Cody, a third-round choice in 2001, is available for trade and Florence is coming on so fast he may end up starting. At safety, there's McNeil at free and free-agent signee Kwamie Lassiter at strong. It was fitting on Saturday that Schottenheimer didn't like what he saw in practice and had a 30-minute "do over."

Schottenheimer's "doing over" an entire pass defense and he likes what he sees.

"Right now, I don't think we are close to where we need to be," outside linebacker Donnie Edwards said. "You've got to realize the four positions in our secondary are all new this year. Ryan moved to safety. Lassiter is new and playing strong instead of free safety. Everybody is learning at the same time. It's just too bad we can't practice more."

Florence is the surprise of the group. Unless he mentally short circuits in games, he has the look of a potential star. He amazes the coaching staff at each practice. At 6-foot, 195 pounds, Florence has the speed to play bump-and-run man and he's physical. They innocently put him back with a bunch of kick returners, and he clearly emerged as the best.

"He's going to be a terrific player," Schottenheimer said. "We've got to find a place for him to play. If you watch practice, Drayton jumps out. He's not only athletic, but he's physical."

Chargers fan were stunned when Harrison was cut and Seau was traded and each moved to playoff-caliber teams in the AFC East looking for leaders. Veterans such as Edwards, Marcellus Wiley, Jamal Williams, McNeil and Lassiter must fill that void.

"Now, I've got to step up and be a leader," Wiley said. "Being a leader is not a job to volunteer for. You have to earn the respect of your teammates. With Rodney and Junior here, you don't want to step on any toes. Obviously, they were great players, so I took a step back."

Edwards is stunned in meetings of his linebackers. He's been in the league eight years. That's more than the rest of the group combined. Starting outside linebacker Ben Leber was a rookie starter last year. Middle linebacker Zeke Moreno enters his third season as does Carlos Polk. Matt Wilhelm, a third-round choice, is in the mix at middle linebacker.

"I look back to 1997 when I was in Kansas City and we have four or five new starters and they were all young," Edwards said. "I was in the middle. Jerome Woods and John Browning and others were all young and didn't know much. We went 13-3. We still have a long way to go here. We are still trying to get everything down, especially with our pass coverage. But I think we will improve."

What's helping is that the handful of remaining veterans on defense feel as though they hit the fountain of youth. Last year, Wiley fought though groin injuries that were so bad that he needed surgery. He looks and feels great. Williams trimmed his weight to 330 pounds and is having his best camp in three years.

Schottenheimer simplified a lot of things on defense, but more than anything else, he incorporated more man-to-man pass coverage. They expect to struggle during the preseason, but the hope is to iron out the problems by the regular season opener.

"We have a lot of young, talented guys who don't know any better," Wiley said. "They are kind of kamikaze in nature. Rookies are different nowadays. They come in now. They are cocky. They make more money than us, but they come in and want to play."

Last year, Schottenheimer had a little bit of a young movement on offense with Brees, a second-year quarterback, rookie center Jason Ball and rookie receiver Reche Caldwell. He tired of watching defenses stack eight players at the line of scrimmage to stop LaDainian Tomlinson, so Boston was signed to open things up.

Boston is a freak of nature. He weighs 245 pounds and runs 4.3 40s. Coaches can't get him out of the weight room because he loves to work on his strength.

"People are going to have to double David because from what I've seen, a single guy can't cover him," Brees said. "He's one of the best out there."

Brees spent the offseason working on getting rid of the ball quicker. At times last year, he tried to "feather" or aim the ball when he was making throws. Boston has sprinter speed. Get him the ball fast and he can produce touchdowns.

"The ball is coming out of Drew's hand a lot quicker," Schottenheimer said.. "When we looked at the tape of last year, sometimes when guys were wide open, he feathered the ball. Now, he's throwing it crisp and sharp."

Of course, the offense is built around Tomlinson, who rushed for 1,683 yards and caught 79 passes. He's a Thurman Thomas-like back that does everything well -- run, catch, avoid. To improve himself, Tomlinson got together with a nutritionist and lost about six pounds to get quicker at 217 pounds.

It's hard to imagine a back quicker than Tomlinson. What's easy to imagine is a battle between Tomlinson and Ricky Williams of the Dolphins for the rushing title.

"I think we have a chance to be one of the best offenses in the league," Tomlinson said. "I'm talking about the day of Troy Aikman, Michael Irvin and Emmitt Smith. As long as we stay healthy, I think we can become that type of offense. Drew is just so much more confident. The thing I see as the biggest difference is his timing and ability to read defenses and throw the ball before receiver comes out of the break."

The interesting part of Chargers practice, though, is that the young secondary is better able to respond to Brees' quick throws. It's an interesting team.

John Clayton is a senior writer for ESPN.com.