Eyre was All-State at Cyprus High School (UT). In 1997 and 1999, he was an All-America selection playing outfield at the College of Eastern Utah.
Eyre was drafted in the 23rd round of the 1999 Major League Baseball Draft by the Minnesota Twins. From 1999 to 2005, Eyre made his way through the Twins' minor league system, playing for the Elizabethton Twins, Quad City River Bandits, Fort Myers Miracle, New Britain Rock Cats, Phoenix Desert Dogs (Arizona Fall League), and Rochester Red Wings.
He made his major league debut for the Twins on April 6, 2006, but was nontendered by the Twins on December 12, 2006, making him a free agent.
The Texas Rangers signed Eyre to a minor league contract with an invitation to spring training. Eyre had Tommy John surgery in August 2007 and missed all of 2008. He returned to the Rangers bullpen for 2009. He spent all of 2010 with the AAA Oklahoma City RedHawks and then became a free agent.
On November 5, 2010, Eyre signed a minor league contract with the Oakland Athletics.
Eyre opted out of his contract in July 2011 and signed a minor league contract with the Baltimore Orioles. He was designated for assignment on December 8, 2011, but was shortly re-signed to a minor league contract. On June 12, 2012 he was released by the Baltimore Orioles.
Following his release from the Orioles organization, on June 19, 2012 Eyre signed a minor-league contract with the Texas Rangers - the organization with whom he pitched in the minor and major leagues from 2007 through 2010 - and resumed pitching in relief for their AAA affiliate, the Round Rock Express, the next day.,
Eyre was named after Willie Mays by his mother, who was an admirer of the Hall of Fame center fielder despite being a Los Angeles Dodgers fan. He is the brother of Scott Eyre, a retired major league relief pitcher. He also has a younger brother, Robert Grace, who is playing in the minor leagues for the San Francisco Giants organization.He married and now has 3 kids.