A week or so after becoming head coach of the Dallas Cowboys in 1989, Jimmy Johnson sat down to watch some film with his defensive coaches, Dave Wannstedt and Dave Campo among them. What they saw was stunning, with Campo later recalling, “We were pretty sure we had more speed the season before at (the University of Miami.”

The objective became quite simple. The roster needed to be overhauled; younger, quicker players would be targeted. For Johnson, stripping football down to its most simplistic level, speed and quickness equal success. Of course, this philosophy led Dallas to a trio of Super Bowl wins, the first with the youngest team in the league, and Team of the Decade status in the 1990s.

Fast-forward 20 years from the aforementioned film session, almost to the month, and Troy Aikman and Jason Garrett are in the Florida Keys, visiting with their former head coach on what was supposed to be a relaxing fishing trip. Instead, Garrett arrived with a notebook overflowing with questions on what it takes to be a successful head coach in the NFL. At the time, Garrett was the Dallas offensive coordinator, but he knew – heck, everyone knew – his time was coming, especially after having turned down head coaching offers from the Atlanta Falcons and Baltimore Ravens.

Johnson later said of Garrett and the trip, “He wore me out.”

Now into his second full season as head coach, it’s obvious some of the sage advice Johnson offered involved adding more speed and quickness to the roster. A byproduct of those personnel changes has been a youth movement of sorts, one which has transformed this current Cowboys squad.

Consider: In Week 14 of 2010, the Cowboys’ 22 starters averaged 29.2 years of age, which was tied for the oldest in the NFL with the Ravens and Brett Favre’s Vikings.

Entering the 2012 campaign, not even two years removed, the average age of the Dallas starters was 26.9, coincidentally on both offense and defense, while the roster overall checked in at exactly 26.0, which was the 14th youngest in the NFL and second to the Philadelphia Eagles in the NFC East. Even last year, Dallas finished as the 10th-oldest team in the league.

That is staggering. In 21 weeks of regular-season games, Dallas went from the oldest team to one of the younger squads in the league, while also going from a 6-10 finish to a promising 2012 campaign kicked off with a road defeat of the defending Super Bowl champions.

Garrett addressed this very subject at the conclusion of last season’s 8-8 finish.

“We had a lot of players, veteran players, who were really good players for us, Pro Bowl-type players for us, and we made some hard decisions to get away from those guys and move on,” Garrett said. “Those aren’t easy decisions to make. We went with some younger guys and we felt like that was the right decision for our football team now and going forward.

“We knew there were going to be some growing pains, but we felt like we had to get on that course and not only do that with a particular position, but also get the structure of our team right from a financial standpoint as well. So we started down that course and we feel like that was the right move for our team in 2011 and moving forward.”

Even in the ever-changing culture of the NFL, the transformation of the roster has been stunning in such a short time frame. Currently, 23 players on the Cowboys’ active roster are 24 years of age or younger, while just five are older than 30. Tony Romo, who turned 32 in April, is the second-oldest player on the team after defensive end Kenyon Coleman, 33.

Let’s look at the changes at each position from the Week 14 home loss against Philly in 2010 to this season:

Quarterbacks: The only real change here is behind Romo, where the team is almost a decade younger in having landed arguably the league’s premier backup in 29-year-old Kyle Orton this summer in favor of the retired Jon Kitna.

Running Backs: Marion Barber out, DeMarco Murray in. Am guessing no one has a problem with that exchange. And while Barber isn’t as old as most of the departed players, his physical running style certainly accelerated his football shelf life.

Wide Receivers/Tight ends: Not much has changed here with Dez Bryant and Miles Austin, although Roy Williams and Sam Hurd have been replaced by some younger, unproven options, including Dwayne Harris, Andre Holmes and Cole Beasley.

Jason Witten and John Phillips remain, with rookie James Hanna now the third tight end after Martellus Bennett signed with the Giants.

Offensive Line: Perhaps at no time in franchise history has the front seen such a dramatic overhaul inside of two years. The starters in Week 14 of 2010 were Doug Free, Kyle Kosier, Andre Gurode, Leonard Davis and Marc Colombo. Combined age: 153, with four of the five at least 31. The starters for Week 1 of 2012 were Free, Mackenzy Bernadeau, Phil Costa, Nate Livings and Tyron Smith, who doesn’t turn 22 until November. Combined age: 130, with none of the five older than 30. That’s a ginormous difference. Take away Free, and that’s 25 years younger among four positions, six-plus years per man.

Defensive Line: Little fluctuation here, although Sean Lissemore and Josh Brent are seeing extensive playing time and were just rookies in 2010. Igor Olshansky has also moved on, while rookie Tyrone Crawford, a third-round selection, has shown promise.

Linebackers: DeMarcus Ware and Anthony Spencer are still on the outside, but there’s been a complete upheaval inside with Sean Lee and Bruce Carter replacing Keith Brooking and Bradie James. In terms of speed and quickness, perhaps no position has been improved more, with the possible exception of cornerback. Brooking and James were both respected veterans, stronger against the run than in pass coverage, while Lee and Carter are two of the team’s better athletes. There hasn’t been a more Jimmy Johnson-like pick over the last two years than Carter, the classic example of “give me the athletic talent, we’ll shape him into a football player.”

Of the eight linebackers on the roster, Ware is the oldest at 30, and six are 26 or younger.

Secondary: Never mind 2010, just look at last year’s team. Terence Newman was 33, Abram Elam and Frank Walker 30. Replace that trio with Brandon Carr, 26, Morris Claiborne, 22, and Barry Church, 24. And yes, Church was on the team, but has now replaced Elam in the starting lineup. Of the six corners currently on the roster, Mike Jenkins is the oldest at 27, while 29-year-old Gerald Sensabaugh is the oldest safety. Not a single 30-year-old among the secondary.

Special Teams: Even at punter, the Cowboys didn’t re-sign longtime veteran Mat McBriar in favor of 23-year-old Chris Jones.

So it really has been across the board, a youth movement much like the one orchestrated by Johnson during his first two seasons at the helm. Only time will tell if the same results follow for Garrett.