It was tough, McCartney admitted, looking back on it.
That injury put a stop to what many considered to be great progress and a potential breakout year in 2011.
McCartney's outlook, and subsequently his attitude, went downhill after that. As a result, his workouts and time around the Puskar Center were less effective.
"My attitude needed improvement," McCartney said. "It was something that I felt deep inside." A four-star prospect out of high school in Miramar, Fla., McCartney didn't have the production of a top five position player as a freshman. In fact, he only caught one pass for four yards and had one rush for two yards.
That's not exactly what West Virginia fans had expected. McCartney wouldn't agree or disagree, but he simply said that he didn't expect any playing time when joining the program and wasn't sure if he would redshirt his first year on campus.
If anything, his first year at WVU gave McCartney experience. Above that, it gave him time to learn to live away from his family and friends in the Sunshine State.
That was his biggest challenge, he said.
"The toughest part of being away from home was not being with my family, friends and things like that. It's just something that you have to get used to," he said. "Last year, it was more of a learning process and getting used to college football. This year, I'm used to it now."
That didn't necessarily mean spring was a breeze. It wasn't.
And when the injury went down, players and coaches around him started to see his attitude problem.
"I said to (McCartney), ‘Listen, you tell me what your goal is, and if you're goal is to play past college, you're going to have to revamp your practice attitude, your tempo, workout regimen,' because I didn't see all of that in the spring," said wide receivers coach Daron Roberts.
McCartney took that to heart.
McCartney wanted to know how Ochocinco managed to be far from home when he played at Oregon State.
"He told me, ‘The one thing that I kept in mind was my dream and where I was trying to go,'" McCartney said. "That's how I'm starting to look at it. For me to get where I need to be, I'm trying to improve my attitude and approach everyday with that happy attitude."
That change was clear on Saturday prior to the team's second fall practice, as McCartney smiled and joked with reporters. He was more open than ever before, sharing what was a critical transformation.
Junior inside receiver Tavon Austin, who was roommates with McCartney over the summer, said he saw the change in mentality first hand.
"He's like my brother … When I come down hard on him, he still will be the same way every day … He really did listen to me," said Austin, who added that when healthy McCartney is one of the "best receivers around."
In just two days of fall practice, Roberts could already see a change, too.
"I think he's made quite a bit of progress in terms of moving his mindset past college freshman to the way I work is going to be at a high level in all respects on the field," Roberts said. "It wouldn't be hard for him to be more productive than he was last year, but I think he wants to do even better. He wants to play at a very high level this year."
McCartney has been much more active and positive in practices. In fact, he could be seen flapping his arms like a bird with a wide smile on his face as he ran toward a practice drill in the second practice.
That smile didn't exist three months ago.
That change in mindset is why Roberts said the sophomore speedster has the tools to be a key contributor in the Mountaineers' high-flying offense in 2011.
"The upside is pretty high with him. He has the quick twitch and the pass-catching ability that you like," Roberts said. "For him, it's a matter of him making up his mind if he wants to be a great player and if he's willing to do what he has to do to get to that point. From what I've seen, I'm sure that's the case."
McCartney has made up his mind, it seems. He wants to go the route of his cousin and play for years in the NFL.
"Now, I just look at it in another way - that God has put me in another place for a reason," he said. "I'm staying positive and pushing forward."