He traded golf for ‘American Ninja Warrior.’ The game pulled him back

When Nathaniel Spencer, who now is 41, was a high-school golfer at the chock-full-o-athletes IMG Academy in Bradenton, Fla., he talked his way into playing center-back in a scrimmage with the school’s supremely talented soccer team. Among the standouts on the field was Freddy Adu, an attacking midfielder who, at 14, had become the youngest athlete ever to sign a professional contract in the United States when he came to terms with the Major League Soccer team, D.C. United. Spencer, who had played competetive soccer growing up but only at the local level, said he didn’t know who Adu was;…