GREEN BAY, Wis. -- He's nearly 6-foot-5 and the film shows an NFL-caliber arm. Few know much else about Ryan Williams.

Green Bay Packers coach Mike McCarthy is among them. But consider McCarthy intrigued by his new No. 3 quarterback.

McCarthy surely will have more pressing issues to deal with when his players return for the start of the offseason program Monday -- a gander at his supposedly trimmed-down running back Eddie Lacy likely is chief among them -- but at some point soon the quarterback-centric head coach will want to begin working with Williams, who has taken an unusual path to his first NFL job.

"He's got an interesting background," McCarthy said recently. "Really until I work with him in person ... but I think there's a reason why we're taking a look at him."

Williams says he's "a shade over 6-5" but reportedly measured 6-4 3/8 at his pro day. He threw all of 52 passes during his three seasons at the University of Miami and none since 2013. The last time he held a full-time job as a quarterback (he's had other jobs; more on that later) was in 2010 at the University of Memphis, where he started 10 games and threw 13 touchdowns and 10 interceptions.

He sat out 2011 as a transfer and backed up in 2012 and 2013. Finally set to be Miami's starter in 2014, Williams tore his ACL in the spring, and that was it for college football.

"It was tough," Williams said in phone interview. "I mean, to sit out your senior year and watch everyone play, but I got over it and learned a lot about football just from the coaches' standpoint."

Williams spent the entire season rehabbing his knee to get ready for the draft. Along the way, he played in the Medal of Honor Bowl, a college all-star game in January 2015, and was named MVP of his team.

With the help of quarterback coach Ken Mastrole -- who played in NFL Europe, had a stint with the Chicago Bears and served as the pre-draft coach for Teddy Bridgewater and EJ Manuel -- Williams prepared for his pro day workout. The Packers liked what they saw and even brought Williams to town for a pre-draft visit.

"They checked my knee, did an MRI, did a couple of tests like flexibility and all that stuff just to make sure I was back to normal, and I passed all their tests," Williams said. "I sat down with [quarterbacks] coach Alex Van Pelt and we watched a little film, and he watched my pro-day film, some game film, the all-star game film, and then I guess they liked me, but they ended up drafting Brett Hundley and that opportunity closed at that point."

Indeed. When the Packers picked Hundley in the fifth round last year, their need for another quarterback vanished. Williams thought he had an undrafted free-agent deal with the Cincinnati Bengals last year, but it fell through for reasons he could not explain.

All the while, he kept in touch with Packers senior personnel executive Alonzo Highsmith, a fellow Miami alum, who encouraged him to keep working.

"He told me, 'Stay ready because something's going to happen. It might be us; it might not be us,'" Williams said. "I didn't really know that Green Bay was going to come back and call me, but I know just from his words, and I trusted everything that he said, that somebody was going to call me at some point and not to just sit around and let that chance pass me by."

But Williams, who is married with a child, also had to make ends meet. While working out with Mastrole, he got a job at a sporting-goods store and also worked odd jobs for friends and family. Williams said he had a couple of workouts for NFL teams last season but nothing materialized until the Packers called him again in January.

Perhaps anticipating that they would lose Scott Tolzien in free agency (he signed with the Indianapolis Colts), the Packers thought Williams was their best option for a developmental quarterback behind Aaron Rodgers and Hundley.

"The pedigree is there," Mastrole said. "He just doesn't have the notches on the belt or the experience that ultimately is the deciding factor for a lot of teams. But he's intriguing. He's a tall guy with an NFL-caliber arm. He's a student of the game. He's smart. He understands the game. The tools are there -- he's just had some bad breaks."