Benavides, who has been hampered by shoulder and knee injuries his entire career, missed the first three games of last season after a serious infection in his right ankle.
But he wasn't about to stop playing.
The native of Los Fresno, Texas, spent several weeks in the hospital, lost more than 20 pounds and had the incident take a toll on him mentally.
"It was devastating," Benavides recalls. "Miserable."
Benavides went from wearing a PICC line in his heart to start the week before the Marshall game to playing against the Thundering Herd. He started the final 10 games of the season and helped the Cardinals to the Belk Bowl.
Now Benavides said he's in the best shape of his life at 285 pounds, he feels as healthy as he has for years and is ready for a huge senior season. He's one of nine seniors on the roster and one of the leaders of the squad.
"For the first time in three years, he's pain free," offensive line coach Dave Borbely said. "You are going to get bumps and bruises but he doesn't have the bad shoulder any more or bad knee any more. It makes a huge difference.
"It's a huge lift for him mentally. He's a whole different guy now."
Benavides joked that he's been injured so much that he understood a recent Internet report that he had suffered a shoulder injury. He reports the story was false and "we had a good time laughing about it."
"I can see why people would think that because I've always been hurt," Benavides said with a laugh. "But I'm fine. I have been doing everything that we have been doing in camp for the first time and I feel healthy."
It's a new feeling for Benavides.
The injury-bug started in high school when he broke his leg and injured the patella tendon in his right knee as a freshman. He had surgery on that and said he was "beaten up and had all kind of bumps and bruises" as a sophomore.
Benavides started all 12 games as a freshman and missed one game as a sophomore. But then the real test for him came last season.
A few days into fall camp, Benavides said he was in bed when the pain was so bad that he started moaning and told roommate Will Stein it was "the worst pain I had ever felt." His right ankle wasn't swollen but he ended up going to the hospital.
"It checked out and they said nothing was wrong," Benavides said.
Benavides went back to practice but the pain was even worse the next evening and he went back to the hospital with the blood tests showing a staph infection.
"They said it was spreading up my let and into my blood," he said. "I couldn't even walk. It was so hard for me."
The first question he asked the doctors was "can I play Kentucky," and later he started hearing people questioning about his injury.
"I had a PICC line to my heart and I was on (medicine) that I would never ever compare to chemo but even the doctor said himself, ‘This antibiotic is as strong as it gets'," Benavides said. "I was throwing up every day and people thought I was just sitting up in the hospital eating hamburgers every day with a hurt knee."
Benavides wasn't the same when he came back, using only three days of practice when he was out of the hospital until he played against Marshall.
But he wanted to make sure he was there for his team.
"People were criticizing me and saying I wasn't the same guy, and the bottom line is that I wasn't the same guy," he said. "When I came back I was so behind. I went from a bed and pipe in my heart to practice and playing against Marshall three days later.
"For me it was like starting a Division I football game and he's not the same guy and he's this and that and I took that personally. I wasn't the same player but my train of thought is that people needed to understand I just wanted to be out there and be there for those guys to be around. I wanted to help my team out."
Now, Benavides is healthy for his senior season.
"What is key for Mario is just staying healthy," head coach Charlie Strong said. "He has the leadership ability because he's a four year starter. He's a really good leader for us. If he can stay healthy, we have a good shot with that position."
Offensive coordinator Shawn Watson called Benavides and fellow senior Alex Kupper "the thump and voice" of the Cardinals' offense.
"Mario has exemplified throughout the whole summer a work ethic with those guys," Watson said. "He's got them together and had film studies with them. He's got them together and they've worked extra work. He's held them all accountable.
"So he's done a great job. He's been hurt throughout his career. He wants this to be his best year, you can tell by the way he's conducted his business."
Benavides has just a few goals for the season, besides team goals, and that's to go out as a leader and stay healthy.
"I want to prove people wrong and show that last year, well stuff happens," he said. "I have done everything that everybody has done in this offeason. I know that everybody always seems to think I am limited because of my injury history.
"But look at it and I don't miss games. I can already tell barring any major injury – knock on wood – I feel feel as good or better than any time I have been here.
"I feel great and I am ready for this season."