St. Joseph, Mo. ? In a busy offseason, the Kansas City Chiefs went after just about everything except what many fans think they lacked the most.

Chiefs defensive end Tyson Jackson stretches during training camp Wednesday in St. Joseph, Mo.

They picked up a 1,000-yard rusher to go with the 1,000-yard rusher they already had and drafted a speedy wide receiver, a tight end and a guard.

Except for Eric Berry, a badly needed safety drafted in the first round, they didn’t do much for a defense that finished a laughable 31st against the run. Everybody is back on the front seven — everybody who had a hand in enabling journeymen running back Jerome Harrison to rush for 286 yards and erase the great Jim Brown’s Cleveland team record.

If fans were surprised that Berry was the only significant pickup on that side of the ball, they were not alone.

So were the players.

“It’s a boost to know they have confidence in us, and they believe we’re going to get it right,” lineman Glenn Dorsey said. “We’ve got a lot of chemistry and we believe we can get it done. And it’s good to know they think so, also.”

Harrison was one of only six rushers who went over 100 yards against the Chiefs’ newly installed 3-4 defense. So rather than a bunch of new faces or an overhaul, management’s mandate to the mostly young, underachieving front seven is clear: Get better.

“As I’ve said before, you can’t get everything that you want or you may think you need,” said coach Todd Haley. “In the NFL, the way I know you can have continued success is to develop the young; the first, second and third-year players you have on your team. That is mandatory. If you’re not developing young players on your team, you probably have very little chance of success.”

And the Chiefs will have little chance of success without a big improvement on the defensive front. One reason for hope is that everybody is more familiar with the defense. A year ago, a new coaching staff took players who were acquired and trained in the 4-3 and switched them to the 3-4. Growing pains were obvious.

“A lot of it was technique,” said defensive end Tyson Jackson, the third overall selection in the 2009 draft.

While the players remained the same, that cannot be said of the coaches. Former Cleveland Browns head coach Romeo Crennel was brought in as defensive coordinator and Tim Krumrie was replaced as defensive line coach by Anthony Pleasant, a 15-year veteran. Crennel’s specialty is the defensive line and he’s been giving that element extra attention.

Another new wrinkle is the presence of grandmaster Joseph Kim. The taekwando expert is working with the pass rushers, teaching them how to use their hands and hips as he’s done with several other NFL teams, including the Cowboys, Dolphins, Browns and Bills.

“It’s going to help a lot,” said lineman Glenn Dorsey. “At first you think some of the things he tells you to do don’t seem natural. But they are.”

Getting better hardly seems like much to ask of the Chiefs’ front seven. Dorsey, Jackson, and linebackers Tamba Hali and Derrick Johnson were all first-round picks. The Chiefs have invested more money in that part of the team than any other.

But they have yet to get full value in return.

“I cannot stress it enough — those are the guys that have to take that next step, whether they’re backups that become starters, starters that become stars or third-teamers that become backups,” Haley said. “Those guys have to take steps and have to make that next step, and that will help us.”

Dorsey, drafted No. 5 overall in 2008, believes it will happen.

“Everybody’s got a better grasp of what the coaches are asking for this year,” he said. “We realize we lost a lot of close games last year and we’re concentrating this year on not making the same mistakes we made then. We challenged each other this year. We’ve been through that hard season and we’re determined to get better. We’re confident in each other.”