With rookies Christian Scotland-Williamson and Jordan Mailata both attempting to make the switch from rugby codes to the NFL, ESPN's Mike Reiss caught up with Nate Ebner -- a Super Bowl winner with the New England Patriots and a U.S. Olympic Sevens rugby player -- on the challenges they will face to make the grade.

Mike Reiss: What did you find most challenging about the transition from one sport to the other?

Nate Ebner: "That's a big question. I grew up playing football. I didn't play in high school. But I've been around it; I watched it every day. It's part of our culture. I transitioned in college too; I was in my second year in college and I had three years of eligibility before the NFL when I walked on, so I had some time to do it at Ohio State.

"That first year was actually a humbling experience, because I thought I would be able to go in and lean on my athletic ability a bit more. But learning the ins and outs and stuff that has to do with football -- offensive formations as a defensive player, and all the different packages, I could go on and on about that. It's basically a lot to learn. It was hard. You play rugby -- there are 15 guys on the field and you don't sub [out].

"I play rugby union, Jordan Mailata plays rugby league, and that's different. Rugby league is a different version of rugby.

"But again, the transition for me was a humbling one. There's a lot to learn, but you just have to grind away at it. That's the biggest thing I can say. My biggest learning years were definitely my rookie year in the NFL. I played three years of college football and didn't really grasp it like I did in my rookie year. So to come straight into the NFL right away with no real experience, it's going to be challenging [for Mailata and Scotland-Williamson]. It's challenging enough as it is just to make it, for everyone, even if you grew up playing the sport your whole life."

Nate Ebner left the New England Patriots for a spell in 2016 to compete for the United States sevens rugby team when the sport made its debut at the Rio Olympics. PASCAL GUYOT/AFP/Getty Images

MR: What surprised you? Something maybe you didn't see coming?

NE: "The amount of studying that you have to do. In rugby, and coming from all my experiences, we studied film a little bit but not to that extent; it's a game where you go out and practice. The amount of film study was a surprise, how much detail went into it. Knowing what I know now, I realized it's what you need to do to gain every edge you can on your opponent and totally understand situations.

"Another surprise is that people who really understand football, it's almost like a second language. There's so much verbiage, and that verbiage changes from team to team and can even change from week to week within the same team. But there's definitely a football language out there that you have to learn and understand. That was news to me as well."

MR: How much time did it take to adjust to the pace of the game?

NE: "It felt fast at first, but that's because I didn't know what I was doing. If you do anything for the first time that requires speed, it's going to feel fast until you understand it. Until you get used to it, it feels like everything is flying.

"The biggest thing I learned is that you can't have any false movement in the plays. In rugby, you can afford a couple wasted steps here and there. The game's constantly flowing, you don't really get a break, so people are tired. In football, you can't afford to be going the wrong direction or take false steps. No wasted movement -- that was new."

MR: What skill sets from football lent themselves to rugby?

NE: "That's such a tough thing to answer. For me going back to rugby like I did, I would say the biggest thing that helped was just the explosiveness and strength you gain training in football, and football made me a more explosive rugby player. It's a different ball, it's a different skill set, even the way you tackle and play defense can be different. People love to correlate the two because they're contact sports and you tackle, but they're also very different sports too. Man-to-man coverage is nothing like being in a ruck and vice versa, there are plenty of examples."

MR: How challenging was the mental switch from one sport to the other?

NE: "For me going from rugby to football -- I had a lot to learn. I couldn't just let the game flow and play because your footwork is important, your eye control is important, what you're thinking about in certain situations is important.

"I think the speed of playing in the NFL helped me slow the game of rugby down. But even with that, my first World Sevens Series event that I did in Singapore felt like the game speed was flying, compared to when I was in the [2016] Olympics just a couple months later. So it still took some getting used to.

"The hardest part for me going from football back to rugby wasn't mental, it was cardiovascular. Trying to transition from six years away from rugby and playing in the NFL where I get a break after six seconds of playing with all-out effort, to having to continually move -- tackle, pass, get up, run, ruck; all those things -- that cardio was a monster.

"It's unlike anything most football players have experienced, and would be a very different kind of challenge to do what those men do on the Sevens team day in and day out. Again, another part of the game that is very different."

Nate Ebner runs on to the field at Super Bowl LI in Houston flanked by Danny Amendola (left) and Tom Brady (right), seven months after playing rugby at the Olympics. Ezra Shaw/Getty Images

MR: How did a rugby tactics book compare with a playbook?

NE: "This is another aspect of rugby that, to me, is more like basketball. Whatever you think of a basketball playbook, I'd say rugby is more similar to that. A football playbook is on a completely different level.

"A lot of basketball is running down the court -- fast breaks, 3-on-2s, 2-on-1s, some double teams so try to find the open guy. Rugby is a lot like that -- quick turnover, fast break, we're going the other way; try to find the overlap, try to find the 3-on-2 or 2-on-1 situation. It's very similar in that regard.

"Every once in a while you will have the set piece, like a half-court play, where you run a certain play and it's not an exact play where something specific has to happen. It's kind of like there are suggestions off this play, like a pick-and-roll [in basketball]. You can keep the ball, or shoot it, or hit the roll guy. You have to take what the defense gives you and rugby is the exact same as that."

MR: How did you find the different shape of the balls?

NE: "I grew up with a football and a rugby ball, sitting side by side. If you're an athlete, we do drills with tennis balls all the time, it doesn't matter -- the ball, you catch it."

MR: How does the buzz of playing in the Olympics compare with playing in the NFL?

NE: "To me, they're completely two different things. Playing in the NFL is a great experience, walking out to play in a Super Bowl, for a championship, that's what you do it for. It is the most-watched event in all of sports. It's amazing to be a part of, special in its own right.

"But walking out with a United States badge on your chest and being on a completely different continent and walking out for the opening ceremonies and having a different country cheer for you because you're representing the United States -- and getting a chill because you know what you represent, what's on your chest and what you're there to do and how this thing is so much bigger than you -- that's an unmatched feeling in and of itself. They're both awesome."

MR: Any final thoughts?

NE: "Professional sports require so much more than just athletic ability. There are going to be challenges along the way. Some people have a lot of potential. This kid [Mailata] is 6 feet 8 inches, 350 pounds and runs like a tight end. That's some God-gifted size and ability. Just look at his highlights. So he has a start right there.

"But he's going to be competing with guys who are similar size and they know what they're doing. I think it's a hard transition. There is a lot to football. But it's doable. I've done it, others have done it. But it's hard, a lot of guys have failed, too.

"It's challenging at the top of anything. You can talk about business, art, sports, etc. The best in the world are the best for a reason. So it's tough... but you can do it if you work hard enough."