MADISON, Wis. -- These 6 a.m. practices are taking a toll on Bret Bielema.
Tuesday's workout is over and the sun is up, providing a postcard view of Camp Randall Stadium from Bielema's roomy office in the northeast corner. Red-eyed and worn out, Bielema slouches in a chair, yawning every 30 seconds or so. A trip downstairs to the weight room will soon recharge the Wisconsin coach, but right now he's struggling.
Bielema wouldn't have it any other way.
"I get anxious about getting out here, so I can't sleep on the front end of it," he said. "But I really like these early morning practices. It maximizes our time.
"There's nothing I hate in life worse than someone wasting my time."
After a 2007 season that was somewhat disappointing by Wisconsin's heightened standards, Bielema saw no need to waste time on a key decision. Dave Doeren was ready to take over a defense that had backslid a bit, so Bielema made a move.
Days after Wisconsin's Outback Bowl loss to Tennessee, Bielema fired defensive coordinator Mike Hankwitz and promoted Doeren, who shared coordinating duties with Hankwitz but took a backseat to the coaching veteran. The decision surprised Hankwitz, who began coordinating defenses when Bielema was 12 years old, but Bielema never second-guessed himself.
"I had to do it because it's what I believed in," Bielema said. "Bottom line, we needed to take a step forward and be more on the same page, more detail-oriented. That's why I made the decision.
"[Doeren] was ready to take the reins."
This spring, Doeren is overseeing a group that returns nine starters, including all three linebackers and all-conference defensive end Matt Shaughnessy. The hope is that these Badgers can reflect the 2006 defense, which ranked second nationally in scoring (12.1 ppg) and fifth in yards allowed (253.1 ypg).
After playing in consecutive New Year's Day bowl games, the hope is high. And like his boss, Doeren isn't wasting any time.
"It's something I've been thinking about for years," Doeren said. "It's been a personal goal, something I've been working extremely hard to get."
When Bielema first interviewed Doeren in January 2006, he saw "a coordinator-in-waiting." He also saw a bit of himself.
Doeren came to Wisconsin from Kansas, where he had served as co-defensive coordinator and linebackers coach from 2002-05. Bielema came to Wisconsin from Kansas State, where he had served as co-defensive coordinator and linebackers coach from 2002-03.
Bielema is just 22 months older than Doeren. When the Wisconsin coaching staff determined recruiting regions, Bielema sent Doeren to southern Florida, the same area he'd scouted for years.
"I heard a lot of people say, 'Hey, you sent your twin down here,'" Bielema said. "Dave and I are very similar in ways, but we're also very different."
Bielema keeps the mood light during practice and picks his spots to turn up the volume. Doeren is all business and coaches at full blast.
"I understand what he likes and doesn't like," Doeren said of Bielema. "I can build off his beliefs, terminology and philosophy and at the same time bring my own personality to it. He's pretty good at letting you do your job."
Doeren bounced around the McLain Center on Tuesday morning, jogging behind plays during 7-on-7 drills and sprinting downfield to congratulate cornerback Otis Merrill after a slick pass breakup. At the end of practice, he put all the defenders through pursuit drills.
"You can definitely sense his urgency," linebacker DeAndre Levy said. "It's his business. Just like our goal is to get to the next level, his goal was to get to the next level of being a defensive coordinator and eventually, maybe a head coach. Just the way he carries himself and tries to get on guys, you can feel that this is where he wants to be."
Urgency was an issue for the defense at the start of the 2007 season. With only one senior starter (tackle Nick Hayden), the Badgers struggled to integrate new players and rarely practiced as a full unit because of injuries to players like linebacker Elijah Hodge and cornerback Jack Ikegwuonu.
Wisconsin won its first five games but allowed 31 points to The Citadel in Week 3 -- the highest total since Bielema had become head coach. After keeping a punch-less Iowa offense in check, Wisconsin gave up more than 30 points in three consecutive games.
The sorry streak ended with a 38-7 whipping at Penn State that all but eliminated the Badgers from the league title race.
"We didn't even show up," safety Shane Carter said. "Definitely embarrassing."
"The Penn State game was the only time that I didn't recognize the crowd on Saturday that we'd coached during the week," Bielema said. "That was a terrible feeling."
Pride took over from that point, and the Badgers allowed just six points in their next two games. They won four of five to close the regular season.
"Why couldn't we just play like that the whole season?" said Shaughnessy, who earned second-team All-Big Ten honors for the second straight season after recording five sacks and 18 TFLs. "We all know what we're capable of doing. Now it's just [about] playing up to that potential.
"It's just picking up where we left off: same calls, same formations."
Doeren, who will call defensive plays for the first time this season, described himself as aggressive but doesn't plan to overhaul the system. Hankwitz called a mix of man and zone blitzes last season, and Doeren said the defense was most effective when pressuring.
How much the Badgers blitz hinges heavily on a secondary that lost top cover man Ikegwuonu to the NFL draft. Carter is back after tying for ninth nationally in interceptions (7), and the Badgers signed five defensive backs in February.
"We definitely want to be the aggressors," Bielema said. "That's something you have to ingrain in their mentality. You can't burn a blitz on every play, but you can be aggressive every play."
Bielema expects to see "a gigantic step" in defensive leadership from players like Carter, outside linebackers Levy and Jonathan Casillas, and cornerbacks Allen Langford and Aaron Henry, both of whom will miss the spring following ACL surgeries. Levy has seen the team play with greater emotion this spring, as shown at the end of Tuesday's practice, when defenders mobbed walk-on cornerback Chukwuma Offor after a leaping interception.
"We tried to end with a bang," Levy said, smiling. "That might set everything off. [Emotion] is something we definitely lacked last year. This year, guys are truly into it. It's genuine right now.
"It's kind of hard to be excited at six in the morning, but we're going to keep that intensity going."
Adam Rittenberg covers college football for ESPN.com. He can be reached at email@example.com.