"Dom Capers thinks the Eagles could successfully transition into a 3-4 defense.

OK, the Green Bay Packers' defensive coordinator - one of the brightest minds behind the 3-4 - wasn't speaking specifically about the Eagles.

Capers actually addressed a general question a day before the Eagles named Juan Castillo their defensive coordinator and reaffirmed their commitment to the 4-3.

But the premise is one that deserves serious consideration, as a pair of 3-4 defenses from the Packers and Pittsburgh Steelers prepare to play Super Bowl XLV.

Pittsburgh has long employed the odd-even seven-man front, but Green Bay switched only last season. So the Packers' successful changeover invites the question: If they can do it, why can't other 4-3 teams (such as the Eagles)?

"I think you can," Capers said. "It's a combination. You've got to have good coaches. You've got to have the ability to adapt your system to the talent that's there at the time. You aren't going to have all the pieces in place."

There are plenty of reasons against changing to the 3-4 alignment, and the Packers certainly could have fallen back on those age-old arguments after they finished 6-10 in 2008. The most obvious one is that they didn't have the right personnel.

When Capers was hired a few weeks after the season, it was assumed that Green Bay would transition to his 3-4 defense. But it wasn't that easy. Head coach Mike McCarthy wanted to move to a 3-4, but like the Eagles, the Packers were missing necessary pieces - a nose tackle and a pass-rushing outside linebacker.

"We had to do some maneuvering," Packers safeties coach Darren Perry said. "And some days, we went back and forth a little bit in terms of how we're going to make it work. But, in the end, we were able to draft a couple of guys."

In the 2009 draft, Green Bay took nose tackle B.J. Raji with the ninth pick overall and linebacker Clay Matthews 17 picks later in the first round. After promising rookie seasons, both blossomed into two of the best at their positions, with Matthews finishing second in voting for NFL defensive player of the year."