GREEN BAY, Wis. -- All that matters is what the Green Bay Packers' defense looks like on Sept. 9, when the regular season opens against the Chicago Bears, and every Sunday (or the occasional Monday, Thursday and Saturday depending on the schedule) after that.

But if things are indeed different this year -- and the defense isn't the liability it has been in so many years since the last Super Bowl season -- then April 17 might be viewed as the turning point. That's when Mike Pettine addressed his players for the first time as Packers defensive coordinator and made the kind of first impression that lingers.

Here they are, almost seven weeks later and nearly five months after Pettine was hired, and the Packers are still talking about that team meeting that started the offseason workouts.

"I really like Mike's first meeting," Packers coach Mike McCarthy said last week. "Like anything in this business, you have one opportunity to make a first impression."

It was in that meeting, a session Pettine said lasted "a long time," where the 51-year-old coach introduced his KILL philosophy -- the "keep it likable and learnable" approach he developed with Rex Ryan with the Ravens and then the Jets. It may be a catchy acronym, but it sounds like just what the Packers needed after all the confusion that ruined their defense toward the end of Dom Capers' tenure as coordinator.

While much of the base philosophies remain intact from Capers to Pettine -- reinforced by the fact that five of Pettine's current defensive assistants were on the staff last season -- this defense could be a streamlined approach to the same principles, especially in the oft-troubled area of communication.

"That's the first thing we talk about during every film session is communication," veteran cornerback Davon House said after Thursday's open OTA practice.

"I love him," House added. "Love the energy he brings. You can feel the juice in the meetings room and on the field. Guys flying around. But it's just the beginning. We're still learning the defense, the ins and outs of it. But so far it's great. Not good, but great as you saw today out there on the practice field."

What House was referring to were the pair of interceptions -- one by first-round pick Jaire Alexander and another by practice-squad linebacker Ahmad Thomas -- of Aaron Rodgers. Both were met with exuberance from the defensive sideline that stood out even during a meaningless late-May practice.

"I think just a different personality now," said cornerback Tramon Williams, who played for Pettine during one of his two seasons as the Browns' head coach. "Obviously you get a good defense and a good system that comes with it, but Mike has a great personality to the point where he's going to let you be a player, but he's going to speak up at the same time when players are not doing what they're supposed to do. So you have that balance between what he brings, and guys love it.

"You've got a guy like, say, [defensive tackle] Mike Daniels and you've got a coach comes in and tells him he's going to let you do what you do, and that's what players love to hear. He's a combination of a guy who understands that players play the game but at the same time, he's going keep a leash on you."

It was Williams who suggested during a recent appearance on ESPN Milwaukee radio that the NFL had caught up to Capers' system. Williams was among those who flourished under Capers and played a key role in the run to Super Bowl XLV, but he also was around long enough to see part of the decline. Williams' last season in Green Bay was 2014; his last play was the touchdown he allowed against the Seahawks in overtime of the NFC title game that season.

Williams re-signed this offseason after three years away in part because of the need for another veteran cornerback and because he has experience in Pettine's system.

"The first couple of years under Dom, we were ahead of the game with it, especially with the players that we had in here," Williams said. "Obviously when you win the Super Bowl, the first thing teams do is turn on the tape to see why these guys are so good. And they start breaking down that film and people start catching up with it, and you have to make adjustments.

"It's funny because Pettine's system is not that far off from Dom's. The system that I was in Arizona [last season] wasn't that far off from Dom, but they had a lot more adjustments to it because you couldn't read what we were doing all the time. From my experience over the last couple of years away, there's adjustments to this defense and guys are making that."

This is Pettine's first job in the NFL since he was fired as the Browns' coach following the 2015 season. He spent his two seasons away immersed in a deep study of the NFL in order to refine and redefine his system. Part of that included a reduction of volume. Where he might have taken 50 different playcalls into a game before, he thinks the number will be closer to 25 now -- another point that was stressed in that first team meeting.

"The biggest thing I wanted them to understand was that it's really important for us to know that it's mindset over scheme," Pettine said. "I know I talked about it then, too, that the playbook, we want to make sure we have a cutting-edge playbook and we do some things that we gear toward the opponent and you have some graduate-level stuff but, at the same time, it shouldn't matter. It's more important how we play and not what we play.

"I told them we can line up in one defense but as long as we play with great passion, great technique that we should be able to stop people if the call sheet's very limited. I think that we've got the buy-in from that. That comes with energy, with focus. The passion piece is big for us as well. It's a kids' game. Sometimes you lose sight of that and guys take it a little bit too seriously and get caught up in some things. 'This is a game, man. Let's go out and have fun.'"