Troy Polamalu's retirement signals end of an era for Steelers defense

In April of 2003 the Steelers did the unthinkable and traded up in the NFL Draft to grab a player. Pittsburgh gave up the 27th overall pick, the 92nd overall pick and the 200th overall pick for the rights to No. 16 overall and a long-haired safety out of Southern California.

A strange confluence of events -- including a verbal deal done with Dexter Jackson falling through -- also had to happen for the Steelers to select Troy Polamalu, but after making the safety a top-20 pick in 2003, Pittsburgh gave birth to the newest rendition of the franchise's legendary defense. It wasn't the Steel Curtain, but Dick LeBeau's unit was a dominant force in Pittsburgh for a long time.

With Polamalu's retirement after the 2014 season, that revolutionary defense that ruled the NFL for nearly a decade is officially dead. 

This isn't a hot take or hyperbole: we can officially turn the page on the Steelers defense from a personnel perspective. The two architects -- Bill Cowher (CBS) and LeBeau (Titans) -- have officially moved on to different posts. 

You can see the cliff right? The Steelers didn't necessarily see it before it was underneath them, although Kevin Colbert and the front office did an admirable job at least attempting to draft players that could fill the roles being lost to Father Time.

The defensive depth chart for the Steelers last Super Bowl in 2008 was absolutely stacked. Aaron Smith, Casey Hampton and Brett Keisel on the defensive line. LaMarr Woodley, James Farrior, James Harrison and Larry Foote at linebacker. Ike Taylor, Deshea Townsend, Troy Polamalu and Ryan Clark in the secondary. 

Virtually the same group of men took the field against the Packers in a losing effort in Super Bowl XLV. Ziggy Hood emerged on the defensive line, Bryant McFadden was officially starting at corner and Lawrence Timmons was at linebacker. 

Fast forward to this offseason's depth chart virtually nothing is the same. Harrison is still listed, somehow, but it's a different player, one who was cast off and temporarily joined the Bengals before returning home. Polamalu is the only other name from 2008. Or was. 

There's plenty of talent with Cameron Heyward, Stephon Tuitt, Timmons, Ryan Shazier, Timmons and Cortez Allen, to name a few of the players on this unit. 

Shamarko Thomas, a 2013 fourth-round pick, is a logical candidate to "replace" Polamalu. 

You can't actually replace Polamalu, of course, especially with a young player whose had limited action on the field. Dude did things that were way beyond freaky in terms of natural football instinct on the football field. 

The combo of timing, athleticism, ball skills and instinct from the safety position is something you might never see again.

Also logical replacement-based change in Pittsburgh? Seeing significant changes in the defense with LeBeau moving on and Keith Butler taking over. We're not talking a drastic philosophical overhaul here: Butler came to the Steelers in 2003 (just like Polamalu, ironically) and worked under LeBeau for over a decade. 

In a recent interview with Steelers.com he hardly sounded beholden to his mentor's signature 3-4 defense.

“I would consider myself a whatever-it-takes-to-win guy. If it’s a 3-4, that’s fine, if that fits your players. I think you have to be able to fit your defense around the players you have,” Butler said. “With what offenses are doing nowadays in the National Football League, they’re playing a lot of three wide receivers and a tight end and a running back, for the most part. In those situations, we’re going to be in kind of a 4-3 anyway, but we’re still going to be able to run the 3-4 also. It gives you a little bit more versatility, I think."

Butler added something else, saying "there's still a place for the 3-4," that indicates he might not see it as viable against current NFL offenses as it once was. 

"I also think there’s still a place for the 3-4, and the reason I think there’s still a place for it is because you also have to be versatile as a defense as offenses are trying to be versatile," Butler said. "So we don’t want to blow it up and say we won’t run the 3-4 anymore. We will run the 3-4, but we will run some 4-3 also, in our sub-package."

You can see some of the makings for a 4-3 defense on the Steelers roster, but it's hardly something Pittsburgh could flip a switch on. That defensive roster is built to run a 3-4 at its base. Maybe the draft changes that but it's difficult to imagine Pittsburgh using picks to stockpile 4-3 linebackers and defensive ends.

Finding them in today's crop of college athletes -- pass rushers are far less traditional and far more EDGE these days -- is hard enough in the first place. 

Next year's team will feature four first-round picks with Shazier, Jarvis Jones, Heyward and Timmons. If Jones can take any kind of step -- he has just three sacks in his career -- Pittsburgh's linebacking corps, also featuring Arthur Moats, is an interesting unit. 

The defensive line's got talent with Heyward and Tuitt, but deploying that crew in a 4-3 formation doesn't feel like the most effective use of the personnel. 

The secondary needs work. Quickly. It could be ugly on the backend if there's no pass rush or run support. 

The lingering lesson here is the Steelers defense that you know and love, the one kids in the 90's grew up viewing as the defense, doesn't exist any more. It was already in the process of changing and Polamalu stepping away just feels like a formal announcement. Time has this weird way of always winning the battle of attrition.