The A's signed lefty Brett Anderson to a four-year contract extension, the team announced (via Twitter). The deal runs from 2010-2013 and includes club options for 2014 and 2015. The extension buys out Anderson's last two pre-arbitration seasons and his first two arbitration years. The options cover Anderson's final arb year and his first year of free agency.

As the Associated Press reported (via ESPN.com), Anderson will earn $500K in 2010, $1MM in 2011, $3MM in 2012, and $5.5MM in 2013. The options are for $8MM in 2014 and $12MM in 2015, with a $1.5MM buyout for each year. Anderson will also receive a $1MM signing bonus, paid in four equal installments between now and November 2011. Overall, the deal will guarantee the left-hander $12.5MM and could be worth as much as $31MM over six years.

In comparison, Brandon Webb signed a $7.5MM extension covering the same four-year chunk of his career in 2004. The Anderson contract overwrites the 2010 deal worth $410K that the A's re-signed him to last month.

The 22-year-old lefty pitched to a 4.06 ERA in 175.1 innings last year with 7.7 K/9 and 2.3BB/9. He has pitched similarly well in his two starts this season. Baseball America ranked Anderson the seventh-best prospect in the game going into the 2009 season.