Jim Street and Jesse Sanchez of MLB.com reports that the Seattle Mariners are on the verge of a four year extension with center fielder Franklin Gutierrez for $20.5 million with a team option for a fifth year.

The Mariners and Gutierrez have been working on this deal since December.  Gutierrez, who was eligible for salary arbitration for the first time, wanted at least three years to cover him until he can hit free agency in 2013.  This contract will cover Gutierrez’s final three arbitration years and his first year of free agent elgibility.

Gutierrez hit .283, 17 home runs and drove in 71 RBIs in his first season with the Mariners in 2009 after spending 4 seasons with the Cleveland Indians.  You can see his complete contract and statistic history here.