PHILADELPHIA (973espn.com) — With Jim Schwartz likely to be Doug Pederson's choice for defensive coordinator, "wide nine" has re-entered the lexicon for Philadelphia Eagles fans and that's a scary proposition for some.

Haunting images of Juan Castillo's disastrous reign as DC under Andy Reid with defensive line coach Jim Washburn seemingly holding autonomy over his position group created an often mindless disconnect, all blamed on the boogeyman that is the wide-nine defensive alignment.

The truth is plenty of teams have used the wide-nine with tremendous efficacy over the years and most who criticize it don't even understand its intent, which in layman terms is the defensive ends in a 4-3 alignment pinning their ears back and rushing the quarterback.

The name comes from the actual alignment which places the defensive ends extremely wide in the nine-gap, outside of the tight end.

The reality, though, is there is no such thing as the “wide-nine defense” and no team in football history, including the disjointed Castillo-Washburn dynamic in Philadelphia, has ever used the alignment as the core belief of a defensive philosophy.

Like any offensive or defensive tweak, there are certainly issues that can be exploited when the edges are only concerned with getting to the QB, things like traps, counters and draws inside the ends or tight ends quickly getting out into their routes without chips or jams are a common occurrence when trying to slow the pass rush. More so, the interior offensive linemen can quickly get to the second level on their blocks.

The real problem with the Castillo-Washburn defense wasn't the wide nine per se, though, it was a lack of communication, coupled with the autonomy given to Washburn who routinely "coached" for his group only and ignored Castillo's vision for the back seven on certain plays.

Schwartz, on the other hand, is a proponent of the wide nine, who has had plenty of success with it over the years, something he explained when he got the DC job in Buffalo before the 2014 season.

"Mostly (the wide-9 is) thrown around by people who couldn't line it up if they wanted to," Schwartz said when asked if his philosophy was a wide-nine-fueled scheme. "That's no disrespect to those people, but I say this: there's 32 teams in the NFL and all 32 of them line up in a wide nine. Not all of them are called wide nine teams. ...It'll certainly be part of our scheme here but that won't define our scheme."

What defines a Schwartz scheme, however, is aggressiveness, instead of the two-gaping read-and-react philosophy that defined what Chip Kelly and Billy Davis wanted on the defensive side of the football.

"We'll be fast, we'll be physical, we want to attack," Schwartz said when talking to the Buffalo media. "We're not going to be a reading defense. There's going to be a lot of defensive linemen that are real happy to play in (the) system."

Fast forward two years and things haven't changed.

-John McMullen covers the Eagles and the NFL for 973ESPN.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen