After playing for Edmonton of the independent Golden Baseball League in 2008, he signed with the Boston Red Sox organization for the 2009 season.

Coello made his major league debut September 2010 with Boston and had a 4.76 ERA in six relief outings.

On February 15, 2011, the Red Sox traded Coello to the Chicago Cubs for minor league second baseman Tony Thomas.

Coello signed a minor league deal with the San Francisco Giants with an opt out clause by June 1.

[7] Prior to his release, Coello had been pitching as a starter in AAA, starting 11 games for the River Cats.

Coello signed a one-year $550,000 contract with the Nexen Heroes of the Korea Baseball Organization in December 2015.