GREEN BAY, Wis. – It goes against everything you probably think run defense is about in the NFL.

Smaller cannot be better.

Not in a world of 325-pound offensive linemen, 250-pound fullbacks and 230-pound running backs.

But after watching their 1,000 pounds of girth on the defensive line last season fall from a top-five run defense at the midway point of last season all the way to 25th by end of the year, the Green Bay Packers are trying a different approach.

Mike Daniels moves into a starting role this season after posting 6.5 sacks in 2013. Matt Ludtke/AP Images

With that kind of decline, the Packers could not stand pat. So they let two of their three starters from last year – 338-pound Ryan Pickett and 325-pound Johnny Jolly -- leave after their contracts expired. Both remain out of football. They planned to surround their 337-pound nose tackle B.J. Raji with a pair of lighter, more athletic defensive ends in Datone Jones (285 pounds) and Mike Daniels (305).

And then they lost Raji to a season-ending torn biceps in the preseason.

So the defensive line the Packers will take into Thursday's opener at the Seattle Seahawks has an average weight of 309.4 pounds. Last year's defensive line averaged 314.3 per man. This year, the Packers have just one 330-plus pounder, undrafted rookie backup nose tackle Mike Pennel (332 pounds).

"You look at the type of guys in which we have this year as opposed to years past, it's … I wouldn't say smaller, but I would say it's a more active, faster, more aggressive D-line as well as linebacker group," Packers outside linebacker Clay Matthews said. "So we feel good about it."

The early returns suggest the Packers might be on to something, although it's always dangerous to make any assumptions based on the preseason. However, with the exception of a 40-yard run by Oakland's Maurice Jones-Drew, who broke three tackles on the play, the Packers' defensive starters did not have much trouble shutting down the run when they played in the first three preseason games.

"People have tried to run the ball on us in the preseason, and we've done a nice job against that," Packers defensive line coach Mike Trgovac said. "Some of the teams we played -- Oakland, Tennessee and St. Louis -- they were not fancy. Oakland, especially, was a power team. I think we'll be OK there."

The Seahawks might be the better judge of that.

The defending Super Bowl champs ranked fourth in the NFL in rushing yards per game (136.8) last season, which is nearly what the Packers allowed per game last season. And the Seahawks' featured back, Marshawn Lynch, breaks tackles by the handful.

The Packers go into that game with a new nose tackle -- free-agent pick Letroy Guion (315 pounds) replaces Raji in the starting lineup -- but perhaps defensive coordinator will play even less of his base 3-4 defense than he did last season, when he used it just 24.8 percent of the time.

The alternative would be to use just two down linemen. Either way, the Packers will be smaller and lighter up front than last season.

"It makes me laugh when people say we're smaller," Jones said. "We're not small. Josh Boyd and I are both 6-4, 290 pounds. That's not small at all. Those are two big defensive ends. I wouldn't necessarily say we're smaller. I would just say we went away from the 330-pound defensive linemen and went to a more traditional guy. A lot of people don't see that, but it's not like we're a small defensive line so we can't play the run."