certainly is big. He packs 293 pounds on his 6-4 frame, having added 23 pounds since signing with the Vols last February. And, after a year at Hargrave Military Academy, he certainly is comfortable in the role of older brother to his fellow freshmen.
"Most of the signees look at me as a big brother since I sat out last year and will be coming in more mature," Walls said. "They even call me 'Big Brother.'"
Though flattered, Walls sees his role as quite a challenge.
"I look at that as a lot of pressure but pressure brings out the best in me," he said. "It's more weight on my shoulders but I'm looking forward to coming in and getting started.
"A bunch of us – David Oku, Nu'Keese Richardson, Eric Gordon, Darren Myles, Jerod Askew and some others – text each other almost every day. They've got high expectations for me, I've got high expectations for them, and we've got high expectations for the team."
How high are those expectations? Through the roof, basically.
"With the coaching staff we have and the group of freshmen we brought in, I think we can get a national championship," Walls said.
With Tennessee coming off a 5-7 season in 2008, you'd assume he isn't expecting a national title in 2009 ... but you'd be wrong.
"I grew up following Tennessee, and I've always loved the Vols," Walls said. "I bleed orange and white, and I think we can win the national championship this year. In 1998 they had lost Peyton Manning and Jamal Lewis got hurt early but they did it. I think we can do it, too, and it starts with us freshmen."
Marlon Walls is doing his part to make it happen. He's working with a personal trainer to ensure that those 23 pounds are muscle, not fat. Vol defensive line coach Ed Orgeron is understandably thrilled.
"I'm 293 pounds now and in pretty good shape," Walls said. "Coach O told me I look like I weigh 260, so that's pretty good."
Besides adding weight, Walls has added strength since February.
"I'm a lot stronger than I've ever been, and I feel real confident and looking forward to practice," he said. "I haven't done a max (maximum lift) but I was bench-pressing 315 last year and now I'm doing 345. And I'm squatting 555 pounds."
Freshman defensive tackles typically lack the strength and physical maturity to contribute significantly in Year 1. That does not appear to be the case for Marlon Walls, however.
"I feel pretty good at defensive tackle," he said. "The guards and center aren't used to going against anybody with my size and speed, so I think I've got a real advantage there."
Scout.com recruiting analyst Yancy Porter thinks Walls has several more attributes going for him.
"Marlon has a great first step and can fight off double teams like an upperclassman," Porter says. "Walls brings a motor that never stops and is a great on-the-field leader."
Following his senior year at Olive Branch (Miss.) High School in 2007, Walls did not qualify academically and had to spend a year at Hargrave boosting his grades. He says his enrollment at UT is now imminent.
"I've got one more course to finish," he said, "but I've been talking to the Clearinghouse every day, and they say everything's looking good. I've got four lessons left, and it's probably going to take about two weeks. I've made all A's so far."
Barring an unforeseen hitch, he'll be attending summer school on The Hill in about a month.
"I hope to get in for second session," Walls said. "That's the plan."
Step 2 of the plan is to make an impact on the Vol defense. From all indications, that will happen sooner, rather than later.
"Coach Monte Kiffin said he has in mind how he wants to use me," Walls said. "And Coach O says he's really excited about me. He thinks I'll work my way into the rotation pretty fast."
Given how thin Tennessee's depth is at defensive tackle, there's an excellent chance Walls will be in the rotation by Game 1.
"I'm a great competitor, so I'm pretty excited about that," he said. "I'm pretty psyched out about this summer and this class of freshmen. We know exactly what Coach (Lane) Kiffin did at USC as far as using freshmen: The lead man is going to play."
Marlon Walls may not be the "lead man" at defensive tackle but this Big Brother probably won't be far off the lead.
"I'm a very intense guy and I like to look in my teammates' eyes to see their intensity," he said. "The year at Hargrave has been tough but it made me a lot hungrier. Now I'm ready to get in there and hit something."
His fellow Tennessee football signees call him "Big Brother," and the nickname fits him like a finely tailored suit.