This story appears in the Jan. 12, 2015, issue of Sports Illustrated. Subscribe to the magazine here.

When his two sons were grade-schoolers, John Bosa bought a trampoline with mesh walls for the backyard of the family’s Miami home. The boys enjoyed the beach and water sports, but bouncing around while perfecting front flips and backflips quickly became their favorite pastime. Soon, afternoon sessions morphed into something less gymnastic: Kill the Man with the Ball. The game involved three or four boys -- Joey; his younger brother, Nick; and one or two neighbors -- and a small red-and-blue football. The rules were simple: One of the boys grabbed the ball, and the others attacked him until he coughed it up. Once, Nick attempted to flip over the oncoming assailants and broke his nose on a trampoline support bar. There really weren’t official winners in Kill the Man with the Ball, just relative levels of survival. “We would go at each other for hours,” Joey says. “I actually miss that.”

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In a way Bosa, a 6’5”, 278-pound sophomore defensive end for Ohio State, has reenacted versions of this mayhem throughout his football life, proving that you can take the kid off the trampoline, but you can’t take the savage pursuit of ballcarriers out of the kid. On Monday the Big Ten defensive player of the year will bring those ball-hounding instincts to another enclosed space -- AT&T Stadium in Arlington, Texas -- where they will be put to the ultimate test against Oregon and its Heisman Trophy-winning quarterback, Marcus Mariota, in the first College Football Playoff championship game.

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Even after All-Big Ten tackle Noah Spence was lost for the season for two failed drug tests, the line has become the bedrock of the Buckeyes’ 17th-ranked defense. Senior tackle Michael Bennett, junior tackle Adolphus Washington, senior end Steve Miller and Bosa have combined for 50 tackles for a loss and 25 sacks. A fearsome package of size, speed and strength, with flowing brown locks and an aw-shucks demeanor, Bosa has emerged as the star, piling up 13½ sacks, 20 tackles for a loss and four forced fumbles. “He’s quick, he’s smart, and he’s coordinated,” Bennett says. “Against Wisconsin, he beat the tackle by sticking inside and then going outside -- the tackle tripped over his own feet trying to keep up. Another play, he picked up the tight end and threw him like a rag doll. The combination of those attributes is really impressive, because he knows how to use them and when to use them.”

Ohio State defensive coordinator Luke Fickell offers another perspective: “There are very few for-sures in recruiting, but Joey is one of those kids that has been born and bred to do this.”

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Joe Robbins/Getty Images

John Bosa played defensive end at Boston College and was a first-round draft pick of the Dolphins in 1987. His brother-in-law, Eric Kumerow, was a linebacker and captain at Ohio State and Miami’s first-round pick in ‘88. Each lasted three years in the NFL before knee injuries forced him to retire. For Joey, football was nearly a birthright, even though he was exposed to all sports -- tennis, golf, baseball, basketball -- and allowed to make his own choice. To this day, John can recall his son’s padded silhouette walking onto a field for the first time, as a fifth-grader. "It was like his practice uniform just fit," John says. "I was like, Oh, he’s done. He’s a football player."

After his playing days John opened a pair of gyms, one in South Beach and another in Weston, each called the Gridiron Club, and Joey became a workout fiend. When he was a sophomore at football powerhouse St. Thomas Aquinas High in Fort Lauderdale, he filled out to about 240 pounds, growing “from the bottom up -- huge legs, big base, big ass,” says John. Joey’s potential became clear at Alabama’s summer camp, where Tide coach Nick Saban watched the defensive end blanket tailbacks on passing routes. Saban tendered Bosa his first scholarship offer that day, and Joey was tempted to commit on the spot; at a restaurant later that day, he asked his father, "How could I do any better than that?" They decided to let the process play out, and Bosa became a top 50 prospect with offers across the SEC and the Big Ten. Eventually, Bosa choose to follow his uncle’s footsteps to Columbus.

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With 7½ sacks he earned freshman All-America honors. Bosa’s self-assessment? “I was awful.” It had taken him five games to get his first sack. “He would come out and be so bummed, like, I stink, Mom,” Cheryl Bosa says. “I’d be like, Oh, for God’s sake, Joey.” Then came a breakthrough, a two-sack night at Northwestern, in which Bosa also recovered a fumble for a touchdown in a 40-30 win. He would collect all but two of his 13½ tackles for a loss in the final eight games, but the unrefined play he saw on film ate at him into the offseason.

“That’s the type of guy Joey is,” Buckeyes senior linebacker Curtis Grant says. “He doesn’t think he’s doing that well, when in reality he is.”

Bosa could bench-press 400 pounds and squat 500 in high school, and such power allowed him to dominate. In the Big Ten, though, opposing linemen were often just as strong. Bosa needed to improve his technique, especially as he faced more double teams and teams slid protection his way. So he and defensive line coach Larry Johnson drilled down on minutiae such as hand placement and developing a more explosive hip turn, which helps a pass rusher get upfield. “Last year I couldn’t flip my hips to save my life,” Bosa says. “I would just rip in gaps and play hard, really. That’s where my plays came from. That doesn’t always work.”

Bosa’s talent became even more apparent. "He has an innate gift of contact balance that you don’t find in a lot of young defensive linemen," Fickell says. “He’s got the greatest core strength of anybody I’ve seen at a young age. He can do unbelievable things because he’s under control.”

In Ohio State’s 42-35 Sugar Bowl upset of Alabama last Thursday, those things included standing up as a middle linebacker and charging into the backfield. “I actually love that play,” Bosa says, “coming downhill on the center and making a move on him.”

It was lost on no one that the victory came against the school that Bosa had nearly chosen, indicative of a larger trend in which the SEC’s lock on talent and championships may be loosening. Asked before the game how he told Saban no during the recruiting process, Bosa joked, “I didn’t. I just didn’t tell him yes.”

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Jonathan Ernst/Getty Images

Joey Bosa’s sack celebration mimics the Twitter shrug symbol (¯\_(ツ)_/¯), fitting for the laid-back beach kid. Demolishing quarterbacks requires a certain ferocity, but Bosa is mostly mellow and unshakable on and off the field. He played piano as a kid and has composed electronic dance music. During Sugar Bowl media day he deadpanned that the best part of his recruiting visit was the trip to the library. He acknowledged that his nickname could be the Italian Horn, based on the charm he wears on a gold chain. “He’s a goofball,” Cheryl says. “He’s always messing with me, poking at me. He’s kind of a pain in the ass, to be honest.”

But Bosa’s shrug is also a savvy bit of branding, a signature move by a guy who dreams of being an NFL star. Some defensive players returning next fall will be bigger (such as Baylor’s 6’9", 280-pound end Shawn Oakman), and some will be more decorated (like Arizona linebacker Scooby Wright III, the Nagurski Award winner as national defensive player of the year). But none will be the face of a program as high-profile as Ohio State’s.

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The fanfare has already begun. After Bosa landed in Orlando for the college football awards show in early December, where he was up for the Bednarik Award (Wright won), a deluge of autograph and photo seekers followed. Lines formed. Ohio State communications staffer Adam Widman, traveling with Bosa, was eventually forced to cut off the admirers. “You would have thought the Beatles were walking through the airport,” says Cheryl, who was with Joey.

It’s a lot to handle, so Bosa has streamlined his existence a bit. He has not abandoned his 54,000-plus Twitter followers, still posting mini movie reviews (“Nightcrawler was great”) and retweeting videos of someone dancing in an Elmo costume. But he has “calmed down,” he says, eliminating the “risky things” he used to post. Bosa also hasn’t produced much music lately. “I really don’t have the time anymore,” he says. It may also be that he wants to eliminate anything that might give NFL teams pause. “I think that’s all of it, to be honest,” Cheryl says. “That’s what he wants.”

He can’t have it now, of course; the NFL requires that a player be three years removed from high school to be eligible for the draft. “It’s a ridiculously arbitrary rule that is unbelievably unfair,” John says. “If he was ready, and scouts told me Joe would be a top five pick this year, and if Joe felt like he was physically ready and wanted to do it, God bless him. I’d let him go."

Joey says he wouldn’t leave anyway, and his father understands why. Bosa is only 19 years old and still growing. “This year was such a big jump,” Bosa says. “I want to see how much I can progress next year.” For the kid who honed his body control and killer instinct on a trampoline, expect that leap to be sky high.