The Wall Street Journal writes about something Packer fans have known for years, and not always approved of:

The Packers have exactly two players drafted by other teams on their 53-man roster. No other team is so overwhelmingly composed of homegrown players—the Seattle Seahawks and San Francisco 49ers are the closest, with all but six of their final 53-man rosters this year.

How the Packers have reached the playoffs for seven straight seasons while largely ignoring free agency owes much to the expert drafting of Green Bay general manager Ted Thompson. But it also speaks to the team’s distinctive approach to coaching up young players, the unusual practice habits of its star quarterback and a fanatical devotion to promoting from within that runs throughout the organization.

As they prepare to face the Arizona Cardinals in a divisional-round playoff game Saturday, the Packers’ approach has become the envy of the league.

The key to Green Bay’s system is the belief that if you bring in players as early as possible, they won’t have “ready-made habits that you get from a guy from another team, the way you did it with his old team,” said defensive line coach Mike Trgovac. “I don’t even know if you would call them bad habits, they are just different from what we would teach.”

Take the case of rookie cornerback Quinten Rollins, who was selected in the second round of the draft last May to fill in for Tramon Williams and Davon House, who had departed in free agency.

There are plenty of things that Rollins needed to learn to succeed at the NFL level, but the Packers had zeroed in on the one skill that he needed to improve, an attribute that is so seemingly innocuous that other teams may not even have noticed: eye control.

Rollins had a habit of peeking into the backfield to get a read on what the quarterback was doing. In college football, cornerbacks coach Joe Whitt Jr. said, players can get away with that. College quarterbacks can usually only throw effectively to one side of the field, the closest side to them, meaning defensive backs can sit back and wait for a quarterback to try to force it to the side they shouldn’t and—voila—snag an interception. Something Rollins did seven times in one season of college football.

“[But] if you use that technique here, you are going to get the ball completed on you,” Whitt said. “Your eye control is very, very important here. Once [the quarterback] gets in your blind spot, you have to change your vision and get it back to your receiver.”

This is the sort of detailed orientation that the Packers put all their new employees through. In fact, Rollins joined a secondary made up of a number of players who didn’t play defensive back very much in college. Demetri Goodson, just like Rollins himself, spent most of his college time playing basketball. Sam Shields played wide receiver. This is no accident.

“I don’t have to un-coach them,” Whitt Jr. said. “I know if they do mess up, it’s something that I taught them.”

The Packers have been remarkably consistent in their internal promotions. They have brought in players from other teams only on rare occasions in recent years—on the current roster, pass rusher Julius Peppers is the most famous example. The team also snagged star cornerback Charles Woodson in 2006.

But under Thompson and coach Mike McCarthy, they’ve mostly stuck to their plan, keeping talented draft picks—like quarterback Aaron Rodgers and linebacker Clay Matthews Jr.—and replacing the less talented draftees with newer, cheaper picks. Rodgers, a first-round pick in 2005, famously replaced the legendary Brett Favre as starter in 2008 after three years being groomed in the Packers system.

To ensure they have a constant supply of in-house candidates, the Packers also use the practice squad differently than most teams—specifically, they have rejected the widespread strategy of signing guys primarily to mimic that week’s opponent. Instead, the Packers practice squad is populated with players they expect one day to suit up for the team. With that in mind, assistant coaches say they coach the practice squad guys as often and as hard as top draft picks, a rarity in the NFL.

Having graduated through the system, Rodgers has even developed practice habits that work to reinforce the team’s developmental strategy.

Rodgers, a two-time NFL most valuable player, is perhaps the most feared quarterback in football these days. But in practice, he can often look downright human. That’s intentional.

For the Packers quarterback, practice isn’t “about getting his feet right or his decisions clean,” McCarthy said. “It’s really about establishing good, full-speed reps” for those around him. Inevitably, that means Rodgers tosses some interceptions in practice.

McCarthy is clear that Rodgers hates getting picked off. He’s rushed down the field to argue calls on make-believe interceptions in practice. But the Packers have come to see these practice sessions as more of a trust-building exercise than a tune-up for Rodgers. That means throwing plenty of what are referred to as 50-50 balls, where both the cornerback and receiver have a chance to haul in the pass.

“He’s trying to see the trust factor, who can come down with it?” said backup quarterback Scott Tolzien. “Who can he trust that, when he throws it up, nothing bad is going to happen? That at the very least, if they don’t catch it, they’ll knock it out of the defensive back’s hands. He’s trying to stretch boundaries and get those opportunities on tape.”

Rodgers’ distinctive approach to practice also showed up in training camp prior to the 2014 season, McCarthy said. Rodgers decided that running back Eddie Lacy needed more “checkdowns,” which are short dump-off passes to the tailback. Practicing these plays doesn’t do much for Rodgers, who could complete those passes in his sleep, but would be crucial in getting Lacy integrated into the offense. So Rodgers spent weeks peppering the running back with checkdowns.

This year in training camp, McCarthy said, Rodgers “wouldn’t pass up too many opportunities to throw to Davante Adams.” The Packers quarterback figured he had a good connection with star receiver Jordy Nelson, so he elected to work on his rapport with Adams, a second-round draft pick in 2015. When Nelson was lost with a season-ending knee injury in the preseason, the Packers simply promoted Adams into the starting lineup.