John Urschel

What’s the likelihood of an NFL player quitting football to pursue a PhD? In Somerville, Massachusetts, Robert Ito speaks to the offensive lineman-turned-mathematician who could calculate the exact probability—and hears about what it’s like when your career goal switches from getting touchdowns and being picked as a first-season starter to dreams of peer review publication and a professorship.

On July 27, 2017, John Urschel, an offensive lineman for the Baltimore Ravens, announced his retirement from football. Only three years into a successful NFL career, Urschel had seen an article in The New York Times two days earlier about chronic traumatic encephalopathy, or CTE, a degenerative disease linked to repeated blows to the head. A neuropathologist had examined the brains of 111 fo...