CAMBRIDGE, Mass. — In late July, John Urschel reported to NFL training camp, just like about 2,800 other players across the league. Urschel checked into the Baltimore Ravens’ hotel, dropped off his bag, and then went to the team facility, where he sat through a full team meeting and an offensive line session. His mind wandered as the coaches went on about goals for the season and what they’d be working on at practice the next day. As a backup offensive lineman, Urschel would be rotating in at center and have to fight all camp just to make the team.

That night, he returned to his room and spent the next couple hours debating with himself whether he wanted to show up the next day. He read math books, played online chess, texted his fiancée, FaceTimed with a friend, and stayed up until 3 a.m., turning the matter over in his head. The next morning, around 6 a.m., he called coach John Harbaugh and told him he was done. He was retiring at age 26, after just three NFL seasons.

“I really, really, really wanted to retire quietly,” Urschel says. “No one notice. Just retire and everything keeps on going, without a single story. Like one little byline, and that’s it. And then there’s nothing else, just ride off into the sunset.”

Instead, when the news broke a few hours later, it made national headlines. It was actually Urschel’s own fault. After the early retirements of Chris Borland and A.J. Tarpley, people assumed that Urschel was another young player leaving the game out of fear of concussions and the long-term affects of CTE. Another study warning of the dangers of football to the brain had been published just two days earlier.

The rest of the day, Urschel’s phone buzzed nonstop from reporters trying to get an interview. He released a statement saying he was excited about taking classes at MIT in the fall and that his fiancée was pregnant with their first child. But he didn’t clarify how he felt about head trauma, and so the reporters kept calling. “That was my worst nightmare,” he says. “I was physically unwell. I was in bed all day, for the first couple of days. Didn’t leave the house. Totally down.”

His phone rang and rang and rang. After a while, Urschel just shut it off.

Steve Boyle for Sports Illustrated

Whether or not he knew it, Urschel had started on the path to retirement more than two years earlier. After his rookie year, in spring 2015, he’d decided to apply to the doctoral program in math at MIT, to take classes in his free time.

At first, the school was unsure what to do with him: the application deadline had long passed. Several department heads sent his application around to one another anyway. Some of them did not know who he was. They Googled Urschel and found videos of him mauling defensive tackles and giving lectures on advanced mathematical concepts.

“Usually we would say, sorry, it’s not the right time, apply again in six months,” says Michel X. Goemans, the current interim head of the department. “But it was a very atypical case.

Urschel had the requisite credentials to be accepted. He had bachelor’s and master’s degrees in math from Penn State, and he already had five research projects either completed or under way that would result in papers published in respectable journals. He was semifamous for being “the football player who does math.”

“We said, let’s take a risk,” Goemans says. “Let’s see how it goes.”

A year later, in the spring of 2016, during the NFL offseason, Urschel enrolled at MIT and took four classes as a full-time student. While his teammates were working out and vacationing, Urschel was living in Cambridge, Mass., studying numerical linear algebra and random matrix theory, spending his days working on complex mathematical proofs, attending lectures by visiting professors, talking math with people who enjoyed the subject as much as he did, loving every minute of life as an academic … until one day an administrator reminded him that, come fall, come football season, he would have to remain a full-time student. He couldn’t go part-time. The MIT doctoral program doesn’t make exceptions in that regard, even for professional athletes.

“It might’ve been relayed to me in an e-mail when I was applying,” Urschel says, “but I’m bad at e-mails.”

Now he had to figure out how to balance playing football and attending school full time, without offending his employer, the Ravens. When Urschel first applied to MIT, he had texted Harbaugh telling him vaguely that he’d decided to “finish his education.” Harbaugh responded that that was O.K. “Then they hit me back after some time,” Urschel recalls, “because I guess they were like, wait a minute, finish your education? What’s he finishing?” At that point, Urschel says he confessed to the Ravens that he was working on his Ph.D. at MIT, and both sides left it at that. It’s unclear whether Harbaugh understood the time commitment that that would involve. “No one really asked,” Urschel says. “And if you don’t ask me…” (The Ravens declined to make Harbaugh available for an interview for this story.)

So that fall, while living in Maryland, Urschel continued at MIT as a full-time student. He signed up for two classes worth of “reading” credits with Goemans and enrolled in one class on Probability Theory. “I had studied that exact stuff at Penn State,” Urschel says. “If you give me a textbook, and the homework assignments are in the book, I do not need to go to a single day of that class.” Instead, Urschel set up a routine that seemed to work for both sides. After a Sunday Ravens game, he’d spend the night and the subsequent Monday off day doing homework, which he would submit to his professor, Scott Sheffield, typed up neatly, via e-mail. When Sheffield would return the assignments in class, he’d call out Urschel’s name and joke, “Well, we know he’s not here…” Urschel only made it to one class all semester, during the Ravens’ bye week. He still got an A. “His work was consistently excellent,” Sheffield said via e-mail, “and he ended up with one of the top scores in the class.”

Meanwhile, Urschel was also periodically checking in with Goemans about the assignments for his reading credits. But “I’m, like, in season, so I’m busy,” Urschel says. “Michel was like, ‘Send me updates, let me know how it’s going.’ I’m really just skimming things. I’m completely blowing off this other stuff.” And the reading that Urschel was “blowing off” covered topics that would be included on his doctoral qualifying exam, which was coming up in February. If Urschel failed that test and didn’t subsequently pass in a certain period of time, he’d be kicked out of MIT. “Basically I’d be screwed,” he says.

After the Ravens’ finished that 2015 season 5-11, well out of the playoffs, Urschel spent all of January cramming for the qualifying exam. He’d work at the chalkboard in his house for 12 hours a day, reviewing the material, making stacks of notes. Then he’d have Louisa Thomas, his soon-to-be fiancée, quiz him into the night. When the test day finally arrived, Urschel was “nervous like I’ve never been before a football game,” he says. It was an oral exam, so he had to stand in front of three professors who peppered him with questions for three hours.

Well, Urschel passed, and that meant that he could now proceed with the next steps in his doctoral degree. He could pick an advisor, start on his thesis and take a lighter load of classes if he wanted. Suddenly it was that much easier for him to play football and pursue the MIT degree at the same time.

Urschel took no courses in the spring of 2017. He worked a lot on a proof involving combinatorial optimization, played a lot of chess with Louisa, and was settling back into the calm, quiet life of academia … until it came time for him to leave Cambridge and report to OTAs. This time, Urschel hesitated. That’s when a thought crept in, a thought that once would’ve seemed blasphemous to him, a thought he’d wrestle with all summer, up until the night before training camp: He felt guilty about his football career taking time away from his math one.

Joe Robbins/Getty Images

Math and football had always been linked in Urschel’s mind, for as long as he could remember, going back to his childhood in Buffalo. When he was 3 or 4 years old, his parents divorced, and he was alone with his mother. As his mother, Venita Parker, juggled working full-time as a nurse and raising a son, she kept John preoccupied with math and puzzle workbooks. Urschel would devour them and then beg for more. His parents were both academically minded—his mother a nurse who’d later become a lawyer, his father, John Urschel Sr., a renowned thoracic surgeon—and he must’ve caught the bug, too. “Mentally, he cannot stay idle,” Parker says. “His brain is always going, and it’s going at a speed that’s faster than mine for sure. If he’s sitting there, his brain has to be playing some kind of mental sport.”

That carried over to school. Urschel was a quiet, shy, fidgety child, the classic smart kid lost in his own thoughts. After testing him, his elementary school recommended he skip the second grade, but Parker balked. She wanted him around kids his own age. “You could sit in your room doing math all day, and then you don’t develop social skills,” she says.

Playing team sports could help with that, too, and football seemed like a logical choice as he grew tall and put on weight. But he was too big to play Pop Warner, and then his middle school couldn’t find a helmet that fit his head. Now Urschel was chubby and insecure and going through the awkward stage that all new teenagers go through, and so his father retired as the chief of surgery at Beth Israel Medical Center in Boston and returned to Buffalo, to be there for what he considered a critical stage in his son’s life.

For about a year then, when Urschel was in the eighth grade, his father would pick him up from school and they’d spend hours working out, lifting and doing homework together. Around that time, the elder Urschel was taking masters-level math, economics and engineering courses at the University of Buffalo, “just to amuse myself, keep my brain going,” he says. Sometimes he’d take his son to class or review homework with him. “Maybe it was something I was thrashing with for a week or so, trying to get my head around,” John Sr. says. “I think I’m doing good with it. Then I give him a 60-second summary, and he’s off and running with it!” This was the first time they had really spent time bonding, father and son. That Christmas, 2004, Urschel’s father gave him one of his first books on mathematical proofs and wrote an inscription on the inside cover. Urschel still keeps the book in his home, 13 years later:

J.C.

To live a happy life, one has to be able to see the beauty that is around us. That sounds easy, but it is surprisingly difficult to do. It requires mental training. Studying mathematics is an ideal form of mental training. Mathematics strips away the dirt of the world to leave the beauty and purity of mathematical reasoning.

Enjoy the beauty of reason!

Love Dad

Once Urschel reached high school and his body filled out, he started playing football, which led to his father only growing more involved in his life, more interested in his development. John Sr. would come to every game and stand in the endzone with a pair of binoculars, a pencil and a pad of paper. He’d watch every snap, jot down detailed notes and relay them to his son over postgame meals at TGI Friday’s.

John Sr. had played five years of college football in Canada, on the offensive line and then at linebacker, while he was studying medicine at the University of Alberta. He had enough talent that the CFL’s Edmonton Eskimos expressed interest in drafting him, he says, but after graduation he decided to retire from football and start with his residency. “It was a no-brainer,” John Sr. recalls. “I had this figured out [early], that the CFL was a dead end.”

He got his football fix instead by teaching his son the game. The summer before Urschel’s senior year of high school, his father decided it was time he learned how to block the way they did in the ’70s. The elder Urschel bought two sets of used pads, took his son to a field, and had him line up across from him. “I just come out of my stance and wallop the kid,” John Sr. says. “And when I say wallop, I just buried my forehead into his forehead and knocked him back. He just looked at me like, what the hell, Dad?” They practiced the technique all summer until Urschel perfected it: explode out of your stance, meet the defender head-on, drive him back.

“That had a huge influence on my football style,” Urschel says. “Fire out, be aggressive, and just smack them”—he claps loudly—“like, right in the head. Smack them with the crown [of my helmet], right on their chin. Just get under them, smack them, and start driving.”

Using that approach, Urschel developed into the best high school offensive lineman in western New York, and that, in turn, earned him a scholarship to Penn State, where he really came into his own. He sped through two math degrees in four years, taught two undergraduate math classes and won the William V. Campbell Trophy, otherwise known as the Academic Heisman. He also started two seasons on the offensive line, was twice named to the All-Big Ten First Team, and made some of his closest friends on the football team. They were the ones who pulled him out of his office on the weekends in time for last call.

“After his last game at Penn State, he had tears in his eyes,” his mother says, “because he knew that he would never on the field with his friends ever again.”

Larry French/Getty Images

Leaving Penn State was the first time Urschel had to choose: math or football. Should he start work on his Ph.D., or continue on to the NFL? He was projected to be a mid-rounder in the 2014 NFL draft, but in math “he was a top-five pick,” his father says. “An elite math mind.”

Urschel thought the choice, like his father’s 30 years earlier, was “a no-brainer,” too—but in the opposite direction. He figured he only had a finite amount of time to play football in his prime; he had the rest of his life to do math. The Ravens picked him in the fifth round, No. 175 overall.

Urschel learned quickly, though, that the NFL lacked the charm of college football. When you’re a rookie, he says, the veterans didn’t “even care to know your name.” Except for one, a guard named A.Q. Shipley. He’d gone to Penn State, too, and their college position coach had asked him to look out for Urschel. Shipley gave Urschel tips about technique, answered his questions and generally made him feel welcomed. Then at the end of camp, the Ravens kept Urschel … and cut Shipley. “John felt bad,” Parker, his mother, says. “He was like, Damn. He was used to the team being this brotherhood. … and then they’re gone.”

Even so, Urschel’s first year in the NFL went as well as could be expected. He began the season as a backup and then was thrust into action due to injuries, and he proved to be a good fit for offensive coordinator Gary Kubiak’s zone-run scheme. Urschel started five games—three in the regular season and two in the playoffs, on the road in Pittsburgh and New England. He now considers starting in those two road playoff games the pinnacle of his career.

All the while, Urschel was still doing math. “Remember,” he says, “I do math in my free time for fun.” He was working on various projects with Ludmil Zikatanov, a Penn State professor who had become a mentor and friend. Specifically, they were making progress on a paper titled, “On the Maximal Error of Spectral Approximation of Graph Bisection.”

It was after that season—after he had started two playoff games—that Urschel decided to apply to MIT. In college he’d been held up as the perfect “student athlete,” and he was proud of that moniker, and he felt as though he’d been neglecting the “student” part since turning pro. “I felt actually kind of guilty,” he says. “I was actually kind of ashamed of myself. I was doing math while I was playing, but I always really prided myself on doing what I wanted to do and not budging on things.” What he wanted to do was play football—and continue his formal education. Plus, he had taken GRE, the standardized test for prospective graduate school students, while at Penn State, and his score would expire in a few years.

A few months later, Urschel started his second NFL camp as a backup again. One day during practice, he was trying to catch the coaches’ eye, pulling around the corner on a power run, when a defender hit him smack in the temple: Urschel was out cold. The next thing he knew, he was in the trainer’s room. Witnesses told him they’d tried carting him off the field, but he’d waved them off. He’d wanted to walk off on his own. Urschel didn’t remember any of that. He had to watch the film to reconstruct what had happened.

Urschel was concussed. He had all of the classic symptoms: headaches, light sensitivity, anxiety, depression. After a few days he tried riding a stationary bike, and he had to stop, because his head hurt. Asked to describe the pain in better detail, Urschel says, “My head would bother me. Just, my head was hurting.”

After some time—Urschel isn’t sure when—the Ravens started giving him the baseline concussion test. Players take the test when they’re in a normal state, and then, after they suffer a concussion, the team re-administers the test to evaluate their cognitive functioning. Urschel had to take the test a number of times; he isn’t sure how many. “I must’ve done really well on that thing [in my normal state], because I was struggling [now],” Urschel says. “I definitely did way too well on that thing.” He remembers being asked questions about colors, shapes and words, as the test assessed his reaction time and memory. It’s meant to be tricky. For example, Urschel remembers that it opened with questions about a list of words—only to come back at the end and ask him to recall those words from the beginning. “I was like, f---, I forgot all of those,” he says.

The real test, in Urschel’s mind, was whether he could still do math. Before the concussion, he had been working on research on a topic called Centroidal Voronoi Tessellation. After the blow to the head, he says, “I tried working on some of this stuff, and it was not going. Just wasn’t going. It was kind of annoying. I was just having a hard time grasping things and following arguments. Visualizing, I had a tough time visualizing. It was just frustrating, really.”

Urschel eventually passed the baseline test and returned to the field, after missing about two weeks. Then the starter ahead of him got hurt, and he ended up starting seven games at center that year. His math ability didn’t return as quickly. “The math took a little longer, just because that’s really high, high-level thinking,” he says. “That took a little while. But before the season was over, I was back.”

Bill Greenblatt/AFP/Getty Images

Urschel’s third season in the league, 2016, started with another injury. During the Ravens’ first preseason game he hurt the AC joint in his right shoulder diving to cut block a guy. He missed the Ravens’ subsequent three preseason games and then was inactive for the first three games of the season. At one point he started worrying about his roster spot. “I don’t even know,” he told his father. “They might cut me next week.”

This was the season during which, unbeknownst to the outside world, Urschel was taking a course at MIT. The class wasn’t his only non-football activity, either. Urschel was doing additional research with a few of his MIT professors, putting the finishing touches on two papers they had been working on dealing with Determinantal Point Processes, and he was also getting more and more into chess, a hobby he’d picked up during college. He’d started practicing more and reading chess books in his spare time, and he’d befriended several chess masters. Before multiple games in 2016, Urschel would text Robert Hess, a chess grandmaster and a friend of his, asking for advice about chess strategy. “I’m like, John, you’re about to play in an NFL game, don’t you need to focus?” Hess recalls. “And he’s like, I am focused.” If it’s any consolation, Urschel only started three games all year and was mostly a backup.

The following spring was when Urschel passed his qualifying exam, settled into life at MIT, and got a glimpse into what life could look like post-football. He also learned then that Thomas, his fiancée, was pregnant with their first child, and that initiated a dialogue about their future and where football fit. Urschel thought about it a lot. He was in a good place financially; he’d made about $1.6 million in three years, and he’d saved a good chunk of that. If he retired, he could focus more on chess, and becoming a chess master, and on his studies at MIT. He had fallen for life at MIT in general. “It’s my favorite place in the world,” he says, grinning from ear to ear. “I love being here. I love every day I’m here. The happiest I’ve ever been in my life is when I’m at MIT. Ever in my life. EVER in my life! Happiest ever.”

Then there was the prospect of becoming a father. “I started thinking, like, you know, I want to start taking better care of myself,” he says. “Especially when I found out [I’m having] a daughter. The thought of, when my daughter gets married, I want to be there to walk her down the aisle. I want, like, longevity.” Was he worried about suffering another concussion and, down the road, developing CTE? “It definitely factored in,” he says.

Urschel decided that 2017 would be his final season; he even told his MIT professors that’d be the case. Only one thing was holding him back from retiring right then: He felt he had an obligation to the Ravens to play out the final year of his contract. Maybe deep down he felt he still owed the game something for all that it had given him. Urschel didn’t tell the team any of this, though. He attended the offseason workouts—as the Ravens installed a new power-run scheme that didn’t exactly fit his skill set—as if nothing were amiss. But leaving MIT was still hard. The first time Urschel left for OTAs, he asked an MIT friend to periodically rearrange the things on his desk, to make it look as if he were still there. If anyone asks, just say vaguely that I’m around.

The debate in Urschel’s head raged on through the summer. As training camp approached, his family and friends noticed he was getting more and more anxious. In those final days, Urschel had several conversations with his father, the only person close to him who wanted him to keep playing. His father’s thinking was: If he played well this year, he could test free agency and get a bigger contract. A psychologist might suggest that, after giving up on his own football career, John Sr. was living vicariously through his son. “He wasn’t accepting that this was going to be my last season,” Urschel says. “He was in denial.”

Then, two days before camp opened, the Journal of the American Medical Association released a jarring study: Boston University’s CTE center had found the disease in 110 out of 111 of brains of former NFL players it had examined. The study didn’t drastically change Urschel’s thinking, he says. He already knew about the dangers of CTE, and he believes the study suffered from self-selection bias—the brains were donated to the research center for a reason, weren’t they? But the study did spark another round of discussions with Thomas, his fiancée. (She declined to comment for this story.)

On the night after Urschel reported to camp, he stayed up until 3 a.m., thinking things over, texting with Thomas, and FaceTiming with Hess, his chess friend. “It was tense,” Hess says. “He genuinely didn’t know what to do. He’s a mathematician, so he’s weighing the odds.” Then Hess asked a question that cut through the clutter in Urschel’s mind: John, did you get to pick the length of your contract? He hadn’t. Everything clicked into place. “I was like, this is a stupid reason to be going back,” Urschel says.

The next morning he called Harbaugh and broke the news. A few days after that he and Thomas left on a nine-day vacation to watch a premier chess tournament in St. Louis—the first vacation Urschel had taken in he doesn’t know how long.

Steve Boyle for Sports Illustrated

It’s a Wednesday in late September 2017, and Urschel and Goemans are sitting at a table, hunched over seven pages of notes spread out in front of them. Goemans, the interim head of the MIT math department, is Urschel’s advisor now, and they’re working their way through a problem that Goemans brought to Urschel after he returned from the chess vacation.

It’s called the Asymmetrical Traveling Salesman Problem. The general idea is that there’s a traveling salesman who needs to visit X number of homes, and the job of the mathematician is to figure out in which order he should visit those homes so as to minimize his travel time. It’s a classic problem, a famous problem, the kind that’s discussed in undergraduate courses all over the world. Goemans has been thinking about it for more than 20 years, and he’s enlisted Urschel to help.

This is Urschel’s life now. He’s taking one class at MIT, working on more research, hosting a weekly show on Chess.com, and preparing to become a father come December. He plans get his Ph.D. in the next few years and then apply for a job teaching and doing research at a top university. He’s as happy as he can be. He only hopes that you not lump him with the others who retired in their 20s over concussion concerns. His case is more complex—like one of his math problems. “I don’t regret playing football,” Urschel says. “[Do I have] some brain damage? I don’t know! I mean, I know a bunch of hits as an offensive linemen isn’t good for the brain. … I figured that, even if worst, worst-case scenario—like if I had issues down the road—I would still have a fair amount of time to do, like, good mathematical things.”

Today, Urschel and Goemans review the Traveling Salesman Problem, and Goemans shows Urschel some strategies and tools that he may be able to use to tinker with the problem on his own. They discuss it for more than 90 minutes straight, no breaks.

“Let’s stop, because my brain is exploding,” Goemans finally says, rubbing his forehead.

“I’m with you,” Urschel says, looking a bit dazed, too.

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