"It's kind of a hybrid position," he said. "You've got to be almost like a defensive end in some situations and almost like a safety or corner in other situations. It's kind of a jack-of-all-trades position."
Nielsen entered training camp No. 1 on the depth chart at LEO. He sat three years behind 2010 Miami Dolphins draft pick, A.J. Edds.
"He's a tough guy, physical guy, smart guy," Nielsen said of Edds. "You learn a lot from a guy like that who's been around the program, a three-year starter. I'm just trying to take the things that I learned from him and hopefully use them to help this team."
Iowa plucked Nielsen from in-state Humboldt High. Scout.com ranked him as the No. 3 WLB nationally in the 2007 recruiting class. He played in the prestigious U.S. Army All-American game.
"I've added 25-30 pounds (since coming to Iowa)," Nielsen said. "Working with Coach (Chris) Doyle and the strength and conditioning staff, you develop a lot more strength, just overall strength in every part of your body. It's just a lot different than what you come in as a 210-pound freshman.
"Physically, I definitely feel like I've changed a lot since coming here a couple of years ago. I know that will help me with being out on the field."
Much like Edds, Nielsen (6-foot-4, 235 pounds) is a cerebral player. They're both academic all-Big Ten selections.
However, while Edds played as a true freshman, Nielsen learned as a reserve. He's recorded 19 tackles, some of which came while being indoctrinated on special teams.
"I played on a lot last year, it helps get your feet wet; adjust to the speed and physicality of the game," Nielsen said. "It helps to get some experience from just what it's like being out there on the field. Hopefully I can carry that over to this year."
"I'm looking forward to it. Hopefully I can have a little bit bigger impact on defense this year. I'm just really excited about things."
Nielsen has been a little dinged up in camp this year as has middle man, Jeff Tarpinian (broken hand). Nielsen felt that an injury to any linebacker wouldn't be cause for alarm because they're all versatile and it‘s a deep corp.
"Really, anyone of the linebackers could do it," Nielsen said of the LEO. "We all have about the same kind of skill set. It's just a lot of repetitions, a lot of practice to get used to the position.
"When you think of linebacker, you don't think of somebody that's standing on the line of scrimmage. You think of somebody that's off the ball, free roam, running around. It's something you've got to get used to over practice. You have to be able to adapt."
For Nielsen, much of his work as gone into coverage skills.
"I've made a lot of progress in that area over the years being here," he said. "I'm looking forward to being able to be out on the field more this year hopefully and make some plays."