Jordan Mailata, a rookie football player in the truest sense of the word, suddenly reached into his locker and plucked out a thigh pad. Just four months ago, he had no idea which body part it was supposed to protect.

“When I came into rookie minicamp, I said, ‘What are these?’” Mailata, the first-year Philadelphia Eagles offensive tackle, tells the Guardian. “They said, ‘They’re your pads.’ I said, ‘Well, where do they go?’ They showed me the shorts, and they said, ‘They go here and here and here.’ And I was like, ‘Oh! Damn!’”

The Eagles had selected Mailata in the seventh round of the NFL draft even though he had never played American football. But Mailata, a 21-year-old Australian, stands 6ft 8in and weighs 346lbs and was so powerful and nimble as an under-20 rugby league player for the South Sydney Rabbitohs that the Eagles thought he could be converted into an NFL offensive lineman.

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How raw was Mailata? Well, the Eagles opener was the first NFL regular-season game he had ever seen live.

“I was sitting on the sideline,” he says, smiling, “and I was like, ‘Shit. I’m on the same team that’s playing!’ It was very surreal. Who would have ever thought that my first ever game I went to was after I made the league? It’s kind of funny it turned out that way. It’s not even just about learning the game. It’s about doing certain things. Just to have that new experience is a unique experience. Every week it’s like that.”

The Eagles’ decision to draft Mailata was seen by many as a gamble at best, and a gimmick at worst. But Mailata impressed the defending Super Bowl champions during training camp and preseason, and he earned a spot on their 53-man roster. It was not an insignificant transaction.

In order to put him on their practice squad to continue his crash course in football, the Eagles would have had to have waived Mailata, thus making him available to other teams. But they were convinced that he had so much potential that another team would pick him up. So the Eagles kept him.

As a third-string left tackle, he has not played in a regular-season game yet, but at least he has seen a few now. His debut is probably still a way off, but Mailata is committed to the process.

“I’m still taking baby steps,” he told the Guardian after practice last week, “and when the coaches think I’m ready, I’ll play.”

Mailata took up American football because, in essence, he was too big for rugby league. The Rabbitohs wanted him to slim down, but Mailata said he had no more weight to lose. In the meantime, clips of Mailata barging through rugby league opponents circulated widely on YouTube, catching the attention of the NFL’s International Player Pathway program. He was invited to a tryout in Los Angeles, then to a mini-camp in Florida in January, then to a regional tryout.

The Eagles traded up to select Mailata in the seventh round of the draft in April, after which Joe Douglas, the team’s vice president of player personnel, said, “We’re excited about the size and athleticism. I mean, those measurables are pretty rare.”

Among those who were excited about Mailata was Eagles offensive line coach Jeff Stoutland. But Mailata was raw. The Eagles knew converting him to an NFL offensive tackle would be a process, and there were no guarantees the project would work. But Mailata wanted to learn the game, and Stoutland had two veteran tackles to help him teach Mailata: Jason Peters and Lane Johnson. Peters and Johnson liked the challenge, too.

“Mentally, the one thing that I know about both of them is they stress the ‘next-play’ mentality, just because that’s how you’ve got to see it,” Mailata says. “Rugby is such a fast, flowing, fluid game. So it’s not like, stop-start-stop-start like you see in American football. Here, it’s like the next-play mentality of attack. Whether you did good or bad, you move onto the next play, so there’s more talk about that.”

Offensive tackles can’t just be thrown onto the field and told to block somebody. An offensive line’s positioning, footwork and handwork are all but choreographed. American football is played with bursts of energy, and teamwork during those bursts is essential.

“What I gained from rugby was body control, which is what allowed me to be called an athlete and had tremendous athleticism. That was not just from playing rugby, but from playing other sports as well,” Mailata says. “Being able to have that body awareness and being able to control it has made it easier to transition – although it’s been really hard.”

Mailata would love to play in a game soon, and he may get the chance if one or more of the three tackles ahead of him on the depth chart are injured, but he says he knows he is not ready – and that he needs to be patient.

“There’s no schedule,” he says, “but that’s one thing I’ve had to learn, one thing they’ve taught me, is to have a next-man-up mentality, to be able to step up for the team when they need it. When we do our training reps, whatever we’re doing here, it’s just like we’re playing a game, and I prepare for the game like I’m going to be playing in it.

“I haven’t played the [first] two weeks, but each week, I’ve been giving it my all. Just by giving myself some good work, I know that by game time if I keep bringing 100% … I’ll get in. What I see out there doesn’t scare me, or shock me. It doesn’t surprise me. I prepare like I prepare for a game.”

Doug Pederson, the Eagles head coach, has quipped that he’d love to give Mailata a chance to carry the ball with the Eagles near the goalline – like William “The Refrigerator” Perry did for the Chicago Bears three decades ago. Mailata is aware many Eagles fans would, too.

“I’d have to lose a couple of pounds first,” Mailata says. “I originally was too lean when I came to the States. I was too lean to play [offensive tackle], so they had me put on some weight. I put on too much weight.” He laughs and pats his stomach, a contented man.