From his days as a blue-chip recruit to three years as Penn State's starting quarterback to becoming a second-round pick by the New York Jets, Christian Hackenberg has always had a training camp to attend.

Not this year. The Jets traded Hackenberg to Oakland in May. The Raiders cut him in June. He spent two months without a team. When July turned into August, Hackenberg learned what it's like to be left at home when everyone goes to work.

The Eagles worked out Hackenberg on Sunday before signing him to be their fifth quarterback. He was at practice on Monday in a No. 8 jersey, nearly three weeks after his new teammates started camp.

"Getting a taste of that, it's not a good sandwich to bite into," Hackenberg said of his time away. "Just really happy to be here, smile on my face, and enjoying every minute of it."

Hackenberg didn't take any snaps in team drills. He participated in individual work and then had a throwing session after practice. The Eagles already have Carson Wentz, Nick Foles, Nate Sudfeld and Joe Callahan on the roster, so even when he learns the offense, Hackenberg will be low on the depth chart. But it's nonetheless an NFL camp. He worked out for the Houston Texans and New England Patriots since becoming a free agent and didn't receive a contract. The Eagles, with a crowded depth chart, were the most interested.

>> LISTEN: Berman and McLane talk Hackenberg, Maddox, preseason game No. 2

Hackenberg is the latest project for an Eagles coaching staff that takes pride in its quarterback development, and he's an intriguing one. Only 23, Hackenberg started as a true freshman at Penn State and left after his junior year. He's had two years in the NFL. He flamed out in New York, but he's the same age as a rookie who was a redshirt senior in college. And at 6-foot-4 and 225 pounds with a strong arm, Hackenberg has tools to develop. He just doesn't have the production to match. There's clearly skepticism about whether he's an NFL-level quarterback, though, considering all 32 teams opened camp without him.

"We're happy that he's here and looking forward to working with him," offensive coordinator Mike Groh said. "I recruited Christian when he was in high school and I've known his family for a long time. He's had his struggles since he's gotten into the NFL. … We've just got to get him out here, and first of all, he's got to learn what to do and then how we want it done. At this point, he's got to crawl before he can walk."

The Eagles seem to be set with Wentz, Foles and Sudfeld as their top three quarterbacks, unless there's an injury elsewhere during the preseason and another team proposes a too-good-to-be-true offer for Foles. But Foles will likely find a starting job elsewhere in 2019, and the Eagles like to have a developmental quarterback on the roster. Hackenberg still has practice-squad eligibility, so if the Eagles are intrigued by what they see the rest of the month, they can keep Hackenberg on the practice squad and continue his development. If they're uninterested after these next few weeks, they can cut him loose. Hackenberg should have the opportunity to play against the Jets, his former team, in the fourth preseason game.

Any NFL job would be appealing to a player out of the league, but for Hackenberg, another appeal was learning from the Eagles' coaching staff and working with Wentz and Foles.

"It's been impressive what they've done since they've been here," Hackenberg said. "Their tutelage has shown on the field. Carson played really well. Nick played incredible."

Hackenberg did not offer much reflection about why it didn't work in New York. He didn't play a regular-season game in his two years there. In six preseason games, he went 59 of 121 (48.8 percent) for 531 yards with three touchdowns and four interceptions.

He also struggled at times during his final two years at Penn State. His best season came as a true freshman under Bill O'Brien, who is now the Texans' coach and passed on signing him.

Hackenberg has spent much of the past year training with Jeff Christensen, a former NFL quarterback who is now a private coach. He said he participated in 86 two-a-days since January. The big focus has been on his footwork, which he said has eliminated the inefficiencies in his delivery. It's now starting to become muscle memory. That training, plus lessons from his own experience, have helped shape his perspective.

"The biggest thing I learned is everyone focuses on results," Hackenberg said. "But the one thing that I found that is really cool is falling in love with the process and making sure you master each step. I think that gets overlooked at times."

There's a humbling reality that comes for any football player, much less one with Hackenberg's history, when they're sitting on the couch in August. That's why Hackenberg admitted to the smiles for simply wearing cleats and football gear again, being part of a team, and staying after practicing for his throwing session. He knows he's behind. Everyone can see the depth chart. But he can also look at Foles' history – and those of a number of other quarterbacks around the league – and see what a fresh start can offer. He has a jersey and place in an NFL locker room, and now the ball is in his hands.

"Obviously, that's an obstacle," Hackenberg said of the late start.  "It's my opportunity, whenever that comes, whatever this is, I assume they signed me for a reason."

Get insights on the Eagles delivered straight to your inbox with Early Birds, beat writer Zach Berman's newsletter for Eagles fans. Click here to sign up.