When Justin Wilcox took over as California's head coach, he promised a hands-on retooling of the Golden Bears' beleaguered defense.

And when Wilcox lined up as quarterback of Cal's scout team during Monday's practice, players realized that their coach had meant what he said -- in a literal sense.

There Wilcox was, coaching up his new defense not from the sideline -- but from smack dab in the middle of the fray, as quarterback with a coach's whistle in his mouth.

"He was blowing the whistle, pressuring everyone to pick up the intensity," linebacker Cameron Saffle said. "It was really cool. It's something that we haven't had in the defensive meeting room. To be able to win at this level, that's one of the things we needed at this program."

Cal has undergone a cataclysmic change in leadership, moving from Sonny Dykes -- an offensively focused architect of the Air Raid -- to Wilcox, a former defensive coordinator.

In terms of coaching focus, the Bears have packed their bags for a sudden move from the North Pole to Antarctica. And Cal's defense needs it: Although the offense was productive under Dykes, the Bears allowed 42.6 points per game last year, ranking second-to-last in the nation. Cal was the country's worst team against the run, allowing 6.2 yards per carry.

Cal is still committed to offensive success, and Wilcox's hire of former Eastern Washington head coach Beau Baldwin as coordinator on that side of the ball attests to that. But on defense, the new regime has completely gutted the old way of operating throughout the first three practices of spring ball.

New defensive coordinator Tim DeRuyter, previously Fresno State's head coach, has wasted no time in scrapping the Bears' old 4-3 scheme and replacing it with a 3-4 alignment. That's a switch that DeRuyter rode to quick success in previous jobs at Nevada, Air Force and Texas A&M. Cal's defenders are in a scramble to learn new positions and the new playbook.

"The first time you make a mistake, [DeRuyter] says, 'it's on us -- the coaches. We'll teach you,'" Saffle said. "But if you mess up again, that's on you. That's the expectation. They're putting these expectations that we haven't had here. ... I'm not going to say that Coach Dykes didn't give the defense as much love, but having a [defensive-oriented staff], we're feeling a lot more love now."

Above all else, Gerald Alexander, Cal's new defensive backs coach, wants the Bears' secondary to play fast while it acclimates to the new regime's ways.

"It's a different system, it's different terminology, it's different techniques," Alexander said. "It's just an entirely different defense for these guys."

For cornerback Darius Allensworth, a fifth-year senior who was around for the entirety of the Dykes era, those are all welcome changes.

"Everything that Coach Wilcox does is at a championship level," Allensworth said. "It's a different type of urgency. [The coaches] expect more. They expect us to do what we need to do. It's just a bunch of small things -- like running every time from drill to drill."

Players say they appreciate that Wilcox himself is participating in those details, leading by example when he throws himself into the fray as scout team quarterback or when he makes a concerted effort to eat breakfast with Cal players every morning.

"That's the type of guy he is," Saffle said. "He wants to have interactions with all of us. The first day he got here, he said, 'I'm not going to give you guys a big speech to get your trust right now, I'm going to earn your trust through the whole process.' And he's been true to that."

The process, of course, can't be finished until the Bears have a chance to record tangible results on the field. But early in this massive retooling process, Cal's defense feels that this complete reset gives it an excellent chance to ultimately achieve a positive reinvention.

"It's a brand new staff, brand new system, and brand new techniques," Alexander said. "We want to understand the players we have, but we don't want to judge them for what they were asked to do in previous years. As long as they're willing to come to work on details, everyone has a chance to make a fresh start and a first impression -- even myself."