GREEN BAY – Before he can become a good route runner, a receiver must first master his release off the line of scrimmage. It’s the foundation for everything to follow. Lose off the line, and little else matters.

A good release mixes boxing with ballet. Receivers react to cornerbacks’ movements, working to gain leverage early so they can separate late. Improvisation, above all else, is key to a clean release. A receiver’s mind must be free, his movements unscripted.

Jeff Janis was describing all this in the Green Bay Packers locker room when suddenly his tone turned reflective. For the longest time, Janis said, his first release off the line of scrimmage was not free and unscripted. Through much of his football life, Janis explained, he knew precisely which movements he’d use for his release before the snap, no matter the cornerback’s technique.

It’s like a receiver trying to start his route blind.

“Not predetermining what you’re going to do off the line,” Janis said, “is something I’ve been trying to work on. Not just taking off and running like a speed release type thing. Just reading the DB and see what he’s going to do, and then going off of that.

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“I think (a predetermined release) is something that I’ve probably done my whole football career. Because I’ve normally been faster than the DB I’m going against, so normally it’s just, ‘I’m going to beat this guy.’ At this level, everybody is pretty fast. So you’ve got to approach things a little differently.”

Before the NFL, Janis didn’t need a crisp release. He was the fastest player on the field at Tawas Area High School. Same at Saginaw Valley State. Janis won his routes because his 4.4-second 40 speed left corners in his dust.

Most corners run a 4.4 40 in the NFL. No longer overwhelming opponents with speed, Janis had to learn the craft of route running. It has taken three full seasons, and even now it would be premature to celebrate his route running.

But Janis, in the midst of another solid preseason, is undoubtedly playing well enough to earn another roster spot this fall. He has made a connection this preseason with Brett Hundley, catching a touchdown from the Packers' backup quarterback in the preseason opener and serving as his lead receiver last week.

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A day after Janis caught three passes for 63 yards in Washington, Hundley offered this rare praise of the Packers' erratic receiver.

“During the preseason,” Hundley said, “you find your guys. Jeff has been that guy for me. He’s very consistent in what he does, and I trust him out there.”

It is unlikely Janis ever will be a top-three receiver in the Packers' offense. His job security hinges on special-teams aptitude, and that’s just fine with him.

Few things in this league have the staying power of special teams.

Yet it would be dismissive to discredit Janis' improvements. Twice this preseason Hundley has praised his route running: after a double move that set up a 20-yard touchdown against the Philadelphia Eagles, and a fade route down the right sideline for a 38-yard catch in Washington.

If nothing else, Janis is showing enough receiving ability to warrant his inclusion on the 53-man roster because of special teams.

“Jeff is really in a groove,” coach Mike McCarthy said. “… He’s an excellent four-down player both on offense and special teams. He’s had big plays both last week and this week. He’s having a great training camp.”

Whenever Janis plays, he seems to make plays.

After missing the entire preseason last year with a broken hand, he has picked up where he left off in his first two preseasons with the Packers. In nine career preseason exhibitions, he’s caught six touchdowns. He ranked among the Packers' top two receivers in yards or receptions in five of those exhibitions.

Big plays have remained elusive in the regular season. Janis’ snaps have been confined almost exclusively to special teams, serving as an injury replacement when warranted. He never has played 250 snaps in any of his three seasons, his most being the 233 he played in 2016.

Janis has one touchdown in 35 career games.

Before he can crack the code to getting snaps within the Packers' offense, Janis knows he first must prove capable of being a complete receiver. Maybe nothing is more important than continuing to master his release.

“That’s something we do practice,” Janis said, “but, yeah, it can be very tough. There’s some guys who are naturally really good at it, and then there’s some guys like myself who may need to work on it a little bit more. So that’s something I’ve been trying to work on."