The Oakland Raiders ranked 29th in total defense last season, allowing 382.5 total yards per game.
Oakland gave up 433 points, fifth most in the league and the third most in team history.
The result: The Raiders finished 27th against the run and 27th against the pass.
Yet when DT Richard Seymour reported to training camp, he said the Raiders had a chance to become a top-five defense in the league.
“Everyone knows the type of players that we have here,” Seymour said. “But now I feel like the coaches are putting us in the right position.”
Kelly pointed to new coach Dennis Allen, the Raiders' first defensive-minded head coach since John Madden roamed the sidelines, and first-year defensive coordinator Jason Tarver, as reasons for his new-found confidence.
“It's just attention to detail, the little things,” Kelly said. “I mean, D.A., he harps on it all day long. The mental errors on the practice field, even in a game, they were down. We cut down on the mental errors and the penalties, people are going to have a hard time dealing with us.”
The Raiders set NFL single-season records for total penalties (163) and penalty yards (1,358) last year. Besides cutting down on penalties, Kelly said the Raiders tackled better Monday night than in any exhibition opener he's played in his nine seasons with the team.
“So whatever they're doing must be working,” Kelly said. “We look a lot better.”
As Denver's defensive coordinator last year, Allen helped orchestrate a defensive turnaround. In 2010 the Broncos' defense ranked dead last (32nd) in total yards, next to last against the run and 25th against the pass. Under Allen, the unit improved in every category, finishing 20th in total defense, 22nd against the run and 18th against the pass.
For the Raiders, Allen and Tarver collaborated to create an aggressive, attacking and unpredictable scheme, complete with multiple fronts, blitzes and coverages.
Gone are the days under the late Al Davis when Oakland relied almost exclusively on man-to-man pass coverage and a four-man rush, rarely blitzing or using zone schemes.
“I think everyone is so excited on defense this year because -- choose my words carefully -- the defense in the past hasn't been as fun,” S Mike Mitchell said. “I feel like (opposing offenses) could know what we're in, every down, by the third series of the game.”
“It's not going to be as predictable,” Mitchell said. “You're not going to know who's (blitzing) or what we're doing. I love it.”
Love seems to be the operative word when it comes to the Raiders and their new defense.
“I love it, I love it,” said Raiders CB Ron Bartell, who played the past seven seasons for St. Louis. “I've been with a lot of defensive coordinators, and most defenses are set around the front four to make plays, maybe the linebackers or the secondary. This defense gives EVERYBODY a chance to make plays on every level."
Tarver, a long-time 49ers assistant who served as Stanford's co-defensive coordinator last year, unveiled Oakland's new defense on Monday night.
“I thought early in the game they did a nice job,” Allen said. “They were attacking, they were aggressive, and that's what we're going to be. And so I thought. J.T. did a nice job of calling the game.”
Tarver said that in this defense, everyone gets a chance to be “activated,” or, in other words, an opportunity to attack the quarterback.
“So when you do have your turn, you need to win,” Tarver said. “Then you get more turns. In the preseason, we're just working on learning how everybody works off of people. If we activate somebody – linebacker, D-lineman, cornerback, safety, whoever it is – then the other guys need to learn how to play around that activation. And we need to help them be right, and those guys need to go fast and make something happen.”
The Raiders' first-team defense appeared to have the Cowboys off balance. On the Cowboys' second series, MLB Rolando McClain delivered a huge hit on TE Jason Witten, dropping him for a 2-yard loss. Defensive end Lamarr Houston nearly sacked Tony Romo on the play, forcing him to scramble and dump the ball to Witten. On second down, Kelly broke through and sacked Romo for a 12-yard loss.
“It's just a great scheme for doing stuff like that," OLB Philip Wheeler said. “That's fun football when you can do that and get people free or make somebody miss and get a sack or something like that. That's when the fun happens."
Follow Raiders reporter Eric Gilmore on Twitter @CBSSportsNFLOAK.