It’s official. The entire Philadelphia Eagles coaching staff and front office essentially has survived a 2011 season that was a tremendous failure.

Even Juan Castillo.

You know, the defensive coordinator who came out of freakin’ nowhere to get that job prior to last season, replacing Sean McDermott despite the fact he hadn’t coached on the defensive side of the ball since he was in charge of the linebackers at Kingsville High School in Texas in the 1980s…

Castillo twisted in the wind for nearly a month after the season ended, but Andy Reid has decided to keep him around despite the fact that the Eagles — who spent tens of millions of dollars on big-name free agents in the offseason — led the league in missed tackles and were remarkably inconsistent both against the run and in coverage.

Nnamdi Asomugha, who was one of the most heavily hyped free agents in recent memory, inexplicably took three months to find his sea legs, while Dominique Rodgers-Cromartie was beaten early and often.

Of course, not all of this can be put on Castillo, who wasn’t given much of anything to work with in the linebacking corps and didn’t exactly have a lot of time to pull things together in an abbreviated, lockout-shortened offseason.

Regardless, this will undoubtedly be a do-or-die year for Castillo, and for that matter, this entire staff. And that’s probably why Reid has brought in Todd Bowles to assist Castillo by taking control of Philly’s high-priced secondary.

The team is set to hire the former Miami Dolphins interim head coach to help Castillo out. Bowles was a fairly hot commodity this month, with his name connected to head-coaching openings in several cities. And while it’s tough to tell if the Rooney Rule helped that cause, it’s hard to see this being a bad move.

Bowles brings the experience that Castillo doesn’t have. He’s coached defensive backs specifically for 14 years running, and that’s exactly what he’ll be charged with doing in Philly.

For now.

Because if the superstar-filled Eagles start 2012 like they did 2011, Castillo isn’t likely to last. And Bowles is there to apply pressure as the clear reliever.

This is a necessary precaution for the Eagles to take. The next apt step would probably be to hire some actual defenders, starting with some linebackers who can, um, tackle guys.

This Philadelphia team has the talent and the tools to win the Super Bowl, and everyone who matters save for DeSean Jackson is under contract for 2012. This staff has to make necessary tweaks in the coming months in order to right the ship, and hiring Bowles was a good start.