GREEN BAY – The Packers didn't just need Damarious Randall, Quinten Rollins and LaDarius Gunter to play last season.

They needed the three rookie cornerbacks to play well.

The departure of Tramon Williams and Davon House in free agency left the Packers with a lot of questions in their secondary heading into the 2015 season.

The trio answered every one of them. While they all had their rookie moments, Randall, Rollins and Gunter contributed to what turned out to be the NFL's sixth-ranked pass defense.

As promising as the debut was, though, cornerbacks coach Joe Whitt Jr. will be the first to say the education is far from over.

"It's a growth and development stage," Whitt said. "Go from running the playbook to playing defensive football, which I think we started to get to mid to the end of the year. They have to have a true grasp of what we're doing … and understand why they're doing it.

"Once you understand the why, you can play much faster. That's where we are right now."

For Randall and Gunter, that process has included learning the slot cornerback position in the Packers' sub-packages after playing almost exclusively outside as a rookies.

Randall, the team's first-round pick a year ago, asked Whitt about playing inside as a rookie, but the Packers already had Casey Hayward and Micah Hyde entrenched in slot roles.

The Packers needed Randall on the boundary, especially when Sam Shields missed the better part of seven games due to a shoulder injury and concussion.

The confident rookie responded with 59 tackles, 16 passes defensed and three interceptions. Still, working inside isn't exactly foreign to Randall. A safety at Arizona State, he often dropped down to cover slot receivers at the line of scrimmage.

Randall ran a lot this offseason to help improve his conditioning in an effort to stay fresh for 60 minutes, if not longer. He also went back and reviewed every catch he allowed.

Given the multiplicity of the Packers' defense, Randall believes it only makes sense to broaden his horizons this offseason like Charles Woodson, Williams and Hayward before him.

"I'm going to definitely do both this year," said Randall when asked about learning the inside position. "I think that's one of the reasons why the Packers drafted me because I was versatile.

"Everybody knows Dom Capers is known for having a lot of versatile players out there and making a lot of plays."

Gunter's situation differs slightly. The 6-foot-2, 198-pound cornerback made the active roster as an undrafted free agent out of Miami but played only a handful of defensive snaps during the regular season.

It wasn't until the playoffs that Gunter received his biggest opportunity, relieving an injured Rollins in the second half against Washington. Gunter held his own on 31 defensive snaps and even broke up a pass intended for veteran Pierre Garcon.

The performance came as no surprise to Whitt. While questions about his speed likely contributed to him going undrafted, Gunter's blend of strength and size made him a good fit in Green Bay.

"I had 100 percent confidence that he was going to go in there and do what he did," said Whitt of the Washington game.

"The kid can play. He can legit play. Pierre has good vertical speed. We respect that guy. Gunt played him well. It's not always about your 40. It's about how you play the game of football and he's shown through the two years I've had him that he plays at a high level."

Whitt wasn't sure at first whether Gunter would be a fit in the slot, but he has been pleased with what he's seen so far.

The undrafted label only has served as fuel to Gunter's fire. Every morning he drives to work, it's about proving he belongs in the building.

This year, he won't be satisfied just being on the roster, either. Inactive for eight games last season, Gunter's goal is not only to make the 53-man roster again, but also the gameday 46.

Getting up to speed on all four cornerback spots is the first step toward making that happen.

"I'm learning (the slot) right now … so I can get on the field more. That's what I'm looking for," Gunter said. "I'm trying to increase my role, so I can add more value to the defense."

While Rollins missed most of the offseason program due to a dislocated finger that required stitches, the former second-round pick was a jack-of-all-trades during his rookie season.

Playing both inside and outside, the 5-foot-11, 195-pound cornerback recorded 35 tackles, a sack and two interceptions (both against the Rams in Week 5).

Although Whitt wants to see the improved tackling from his group during this upcoming season, he takes no issue with Randall's and Rollins' approach.

In fact, he credits Rollins for being the unit's "most impactful tackler" despite the fact he only played football during his senior year at Miami (Ohio).

"I definitely feel different," Rollins said. "The game has slowed down a bunch for me. Hopefully as the years keep going by, it's going to slow down even more. This time last year we were still learning the playbook. This time this year I know the playbook."

Defenses can't have enough cornerbacks given the pass-centric nature of today's NFL. The more offenses spread out, the more versatile players needed to keep pace with them.

Time will tell where Randall, Rollins and Gunter line up this year, but their work this offseason will go far in making sure they're ready when called upon.

"I believe from Guy 1 to 9, the gap is closer than any other of my nine years here," Whitt said. "Sam is probably the top guy, but that gap isn't as far as it's been. They know they can't take days off. It's very even, but they push each other and they pull for each other."