When Myles Jack tore up his knee in September, he took what many perceived to be a risk. He withdrew from UCLA and spent the last six months preparing for the NFL draft. Now projected to be a top 10 pick, Jack is ready to fulfill his dream. (4:01)

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MYLES JACK DOES not pause. He does not look down to register the memory of himself, limp and screaming. Yes, he concedes, it is a little strange to be here, back on the 30-yard line of UCLA's practice field, where his college career ended on a cool afternoon last fall. But at least for now, walking across the field before his pro day in March, he won't let himself revisit the past, won't relive the moment that led him to take an unprecedented risk.

Jack is back on UCLA's field for the first time in six months, since he withdrew from school and left his team, betting that he could best prepare for the NFL on his own -- staking his career on a decision for which he could find no precedent. On April 28, he'll find out whether that gamble paid off.

In his first year at UCLA, Jack was both the Pac 12's Offensive and Defensive Player of the Year. Mark J. Rebilas/USA TODAY Sports

IT WAS TUESDAY, Sept. 22. The Bruins were 3-0, ranked ninth in the country, and Jack was starting his junior year as the team's unquestioned star. His skill set was varied and striking -- a linebacker/running back/safety. His surname made his nickname inevitable: Here was Myles Jack, the Jack of All Trades.

The team was preparing for a trip to play Arizona. Jack lined up off the line of scrimmage for seven-on-sevens, and when the ball was snapped, he dropped into coverage. Quick slant. Just a moment after he began to backpedal, Jack exploded forward. He met the receiver, ball and men hitting the same spot at the same time. Limbs tangled. Together they tumbled to the ground.

He felt a pop and thought, "That's weird." He stood, ready for the next play, then collapsed. Heads turned as he started to scream.

Panicked, he went to the training room, sat on a table and tried to straighten his right leg. The pain shattered him -- sure enough, his meniscus was torn. He called his mom, and in his voice she heard something small and frail. He went into surgery that night, and soon his doctor gave a prognosis. No running for four months; no football for six. The biggest season of his life was over less than a month after it began.

When Myles Jack left UCLA three games into his junior year, he knew he was taking a risk. Ture Lillegraven for ESPN

AFTER HIS SURGERY, Jack surrounded himself with darkness. He lay in his bedroom, door shut, eyes closed, and willed the time to pass. That weekend he watched UCLA play Arizona, but the sight of his teammates, together and healthy, was crushing. School felt like a nuisance, so his work started piling up. But the lethargy devastated him. He picked up the phone and called his mom and asked a crazy question. What if he dropped out? What if he left UCLA and found a private trainer to help him prepare for the draft? He could rehab full time. No class, no campus life, nothing but the daily work of repairing his knee.

His mom, La Sonjia, was skeptical, but Myles implored her: Do some research. She began making calls. She talked to UCLA's compliance office and its registrar, to NFL agents and to the NFL Players Association. The feedback made one thing clear: This was a risk. The moment Jack hired an agent, he'd forfeit his college eligibility. If rehab went poorly, his draft stock could plummet and he'd be left with nowhere to return.

Yet the upside was clear. An agent could connect Jack to some of the best trainers in the country. Those trainers could offer undivided attention, giving Jack more targeted care than he could receive at UCLA. Jack talked to a few of his closest friends on the team. His roommate, linebacker Deon Hollins, asked him: "What other opportunity are you going to have to make that much money that fast?"

Hollins says Jack was born to play football, and if he were injured again, it could be debilitating. "He gave his heart to this team. So if he wanted to go, I told him to go."

The following Sunday, Jack walked to coach Jim Mora's office and announced his decision to the man who'd helped him become a star. His college career was over. Jack was gone.

Mora listened, surprised. "'I've been through this process with a lot of teams,'" Jack remembers him saying, reflecting on his time in the NFL. He knew that scouts viewed underclassmen as risky, let alone an injured player with less than two and a half seasons of college football. Jack could go, Mora told him, and he'd support him. But a lot could go wrong. And if it did, Jack would be left with no one to rely on but himself.

He filed his papers the next day.

When Mora spoke to reporters that week, he reiterated that he supported Jack but spent more time on the ways he could fail. "I think it's risky to do this," he said. "Having been on that side [as an NFL coach], there's going to be a lot of speculation as to what he is and where he fits. And as I told Myles on Sunday, NFL teams are very, very conservative, and if there's any question whatsoever, they'll pass on you in a heartbeat."

Jack now says that Mora's comments echoed what he'd told Jack in private, but the week he left school, he was taken aback, telling NFL.com, "It definitely surprised me, but I don't know -- maybe that's what he felt."

Jack's vertical leap and bench press results at UCLA's pro day would have ranked among those of the combine's best LBs. Damian Dovarganes/AP Images

THE FIRST TIME an NFL coach called him a punk, Jack admits he was a little surprised. It was February. He was in Indianapolis, sitting in a meeting room at the NFL draft combine. "Whoa," he thought, registering the comment for a moment. "Why am I getting called a punk right now?" Turns out the second he withdrew from school, Jack became affixed to a certain narrative. Things got tough. Jack quit. The end.

So now, when Jack interviews with team officials, they arrive well-armed to perform jock psychology. The "punk" label has been dropped multiple times. They ask whether he's a bad teammate. They wonder whether he'll start locker room fights, even speculating that he really left school because he was afraid that someone might steal his girlfriend.

At pro day in Westwood, though, the NFL reps have little interest in seeing how Jack's mind ticks. They just want to watch how his body moves, eager to see what has emerged after six months of hiding. He measures his vertical leap at 40 inches and his broad jump at 10 feet, 4 inches -- both of which would have placed him among the top linebackers at the combine. On the field, he cycles through drills with ex-teammates; they cheer one another on as if this were just another Bruins practice, as if Jack were still on the team.

When he moves, Jack devours space, his body rolling like a sentient avalanche. Hips high and chest higher, feet pointed in the right direction. And yet, here and there, he buckles. The knee catches itself, as if pulled down by some invisible weight. "I don't think Myles is 100 percent yet," Mora says minutes later. "I've watched him for a lot of years. I know what he's capable of, and he's capable of greatness."

Later that afternoon, Jack is quiet, disappointed. "I wanted to do better," he says. With every plant, he felt a reminder that muscles and tendons still aren't working as they should. But no one else -- his mom, his agent, a family friend -- is particularly concerned. Give it time. The knee will be fine.

The first post-workout stop is Roscoe's House of Chicken and Waffles, and Jack smiles and orders his usual -- four legs, two waffles, heavy on the hot sauce. "It's been way too long." He was a regular here once. Now each bite feels like an extravagance, a decadence he gave up when he left UCLA.

His new routine began last November, after he moved to Phoenix to work with Brett Fischer, a trainer his agent had found. Fischer is the physical therapist of the Arizona Cardinals and trains NFL and MLB players privately from his own gym. With Jack, he wanted to completely transform his body. Change started with a new diet: salmon, chicken, vegetables and fruit -- and little more. No more sugar. No wasted carbs.

Jack worked out six days a week after leaving UCLA to rehab his knee. Gary A. Vasquez/USA TODAY Sports

After a few days, Jack showed up for his morning workout, weak and pale. The night before, he had sweat through his clothes. He'd begun to shake. He had taken a shower and then soaked his clothes again. The cycles continued, eight showers in all, until finally, too tired to keep shaking, Jack drifted off to sleep. "You're detoxing," Fischer said. While at UCLA, Jack had consumed so much sugar that now his body reacted like an addict to its loss. He flailed his way through the workout. Only later that day did the sweats and shakes fully subside.

"When Myles came here," Fischer says, "he didn't really have the physique that I thought a player like that should have had." Muscles seemed dormant. Fat appeared where it shouldn't have. Jack had thrived at UCLA on will and natural athleticism. Now he trained five or more hours a day, six days a week, even on Thanksgiving and New Year's Day. Outside that gym, he imagined, the world was a void.

He fell in love with that solitude, the metronomic rhythm of every day. His family had moved often -- Phoenix and San Francisco and Atlanta and Seattle and back to Atlanta. Always new schools and new coaches and new friends. Only here, in this massive gym in the desert, did he find the consistency of routine he craved. Friends were absent. Classes didn't exist. There was only each weight, each step, each movement.

For the first time in his life, Jack was untethered from a team. Here and there, he chatted with a few NFL vets who came in for workouts, including Cardinals All-Pro safety Tyrann Mathieu. "This is lonely," says Mathieu, who was forced to prepare for the draft on his own in 2012 after he was dismissed by LSU. "It's so lonely. You're used to being with your brothers. You're used to having your whole days mapped out. Now you have to do it all on your own."

Back at Roscoe's, Jack rises and walks to the exit. When he takes it all into account, he says, the progress is clear. His 40-inch vertical would have been impossible if he were carrying extra fat. At the combine, he benched 225 pounds 19 times -- 12 more than he managed in college. He is still working his way back to full fitness, and soon he'll announce that he won't run the 40-yard dash before the draft. Still, he's expected to go high in the first round ("I wouldn't be scared by the knee," says longtime NFL scout Dan Shonka, who now runs an independent scouting service).

As he steps outside the restaurant, his mom puts her hand on his shoulder and reminds him of where he now stands. "Let me tell you what one of these coaches said to me today," she says. "He told me that they want you, but the only way they're going to get you is if you get in trouble."

Now she laughs, big and joyous, with her whole body. Jack takes a seat on a bench. He grins and shakes his head.

Jack is expected to go in the top five of this month's NFL Draft, according to most mocks. Ture Lillegraven for ESPN

ON A MARCH afternoon, sitting in a hotel room high above Scottsdale, Jack says of his decision: "I didn't see it as a risk. You have to bet on yourself. If you won't bet on yourself, nobody else will. I feel like everybody's made that decision in their life where they bet on themselves, and that was mine.

"There's going to be one team out of 32 that likes me. I can just feel that. You only get so long to play football. I have a once-in-a-lifetime opportunity. So I went for it."

By taking command of his recovery, Jack continued to shift the paradigm of who controls an athlete's body. As a recruit, Jack told reporters he understood that college football was a business. As a freshman, he took out an insurance policy. He chose linebacker over running back because he loves the position -- plus, he knows that the NFL tends to treat runners as disposable toys. At every step, he has held autonomy over his career.

The next night he's down by the pool bar of Scottsdale's W hotel, sitting on a couch in a greenroom surrounded by men and women in various states of undress. The occasion: a "Suits and Sneakers" fashion show, featuring a gaggle of local models and a handful of athletes with Arizona ties.

The clock ticks past 11, and Jack retreats to the dressing room, where he dons a blue suit and red bow tie. This is the life he chose. When he arrived at UCLA, he picked the number 30 for a reason. "Three and out," he says. "That was my mantra." He thought he needed three seasons of football. Turns out he needed only two and a quarter. Most mock drafts agree that he won't fall lower than No. 5 to Jacksonville. Says Mathieu: "Give him three years and he's going to be one of the top five linebackers in this league. You hardly ever see someone that big and that explosive. If he's not even 100 percent now, I'm terrified to see what he looks like then."

In Scottsdale, the music thumps. The crowd squeals. When Jack's name is called, he slowly walks the length of the catwalk. Whatever risk he assumed has long ago vanished, replaced by the staggering nearness of a once-distant dream. Jack approaches the end of the catwalk, and he pauses. He smiles. He gives a thumbs-up. Cameras flash, and the pool glimmers. He lingers, just for a moment, and then he turns around and walks away.