MADISON - It hasn't been difficult for University of Wisconsin defensive coordinator Dave Doeren to make calls the past few games.

"We aren't calling a lot of things right now," Doeren said. "Guys are just playing. It makes it easy. You just call your base defenses and throw a changeup in there every now and then - so they don't know where you're at - and watch them run."

It's yet another example that players, not schemes, usually make the difference in football.

"I think one thing I really like about Dave and the defensive coaches, they haven't tried to reinvent the wheel," UW coach Bret Bielema said. "I would say in our last four, five games, (we) would have one of the smallest game plans/call sheets that we've had.

"I think the result of it is we've played well. I don't mean to beat up our guys, but sometimes the less you know, the faster you can play and that's really come up these last couple weeks."

Ask Bielema about the overall improvement on defense this season and he'll point to all the players who weren't on the field a year ago.

"There's so many guys that are playing for us right now that weren't in that mix (last year)," Bielema said.

Among the players: sophomore defensive end J.J. Watt, a transfer who spent last season practicing on the scout team; the defensive tackle rotation of Dan Moore, Patrick Butrym and Jeff Stehle, who got limited playing time last year; middle linebacker Culmer St. Jean, who played sparingly on defense before the bowl game; redshirt freshman linebacker Mike Taylor, who was leading the defense in tackles before a season-ending knee injury; and freshman linebacker Chris Borland, the current co-Defensive Player of the Week in the Big Ten Conference.

While those fresh faces have certainly made a difference, Doeren believes the lessons learned from last season have also had a big impact.

"There's no question, you've got to get knocked down to the foundation of who you are, I think, and face adversity and grow and learn from it," he said.

That happened last season to a defense that played well at times, but also came unhinged at critical moments. Those problems have been well-chronicled: a failure to get off the field on third downs, a lack of forced turnovers, too many penalties and sloppy tackling.

"We gave up so many third-down conversions last year off of critical points in the game where we would make a stop, but we would be penalized and we'd give them a first down," Bielema said.

"(It would) just drive you nuts. Well, the only way to (fix) that is to eliminate the penalty. It's not to eliminate the player. It's not to eliminate the scheme."

The defense has been especially good in the five Big Ten Conference games. It starts with stopping the run. In conference games only, the Badgers rank first in run defense, allowing 73.8 yards per game and 2.5 yards per carry.

"Better tackling, support has been there," Bielema said of the factors. "I think the edges of our defense have been there primarily. ... You haven't seen the big runs."

In conference games, the UW defense also ranks first in opponent's third-down conversions (30.3 percent) and opponent's first downs (70). The Badgers are tied for the fewest penalties (22) with Michigan.

Overall, they have forced 20 turnovers, which ranks No. 13 nationally and is only two fewer than they came up with all last season.

While the front seven has been solid all season, the secondary is coming off its best game in the 37-0 shutout of Purdue, when it allowed 81 passing yards.

"It's obviously the best four quarters we've put together on defense," Doeren said. "It's probably the best all three position groups have played together on defense.

"People talk about Purdue dropping balls and this and that, well, we were re-routing them and contending (passes) and in the face of the quarterback, too. Some of that was manifested by how we were playing. Some of it was their lack of concentration. It was very fun to watch."

Sometimes, when teams play well, coaches talk about going over the tapes quickly and moving on to the next opponent. But Doeren wanted to spend some time Sunday showing the defensive players precisely why they are having success.

"When you do things right, one play at a time, the end result is going to be something you're pretty happy with," Doeren said of the lessons going forward.

"Whereas, if you start to get comfortable or lose focus, all of a sudden you have your back to the wall more than you want to."