Barnwell began his sportswriting career while a student at
Northeastern University as an intern for
Football Outsiders, a football statistics and analysis website. He remained at Football Outsiders until 2011 when he was brought on to write at
Grantland, a sports and pop-culture website started by
Bill Simmons in affiliation with
ESPN. While at Grantland he also wrote about the
NBA,
UFC,
Premier League and
sabermetrics, and frequently appeared as a guest on
The B.S. Report. Barnwell, along with fellow Grantland writer Robert Mays, hosted the
Grantland NFL Podcast from August 2013 until October 2015, at which point ESPN announced that it was ending the publication of Grantland. Prior to Grantland's closure, the
Grantland NFL Podcast missed several scheduled release dates over a period of two weeks without public explanation, leading to speculation that Barnwell and Mays may have been engaged in a dispute with interim editor
Chris Connelly. Regarding football analysis, Barnwell frequently cites a team's
DVOA. While working at Football Outsiders, Barnwell developed a
metric called
Speed Score, which uses an individual football player's weight and
40-yard dash time at the
NFL Scouting Combine to predict future performance. In fourth down situations, Barnwell has written that football teams are unlikely to be as aggressive as they should be, arguing that average win probability usually goes up when a team elects not to
punt. In 2015, he assumed full-time writing duties at ESPN.com. ==Personal life==