Thornton Sticks with Sox, Signs Two-Year Extension

In a bit of unexpected business Sunday morning, the White Sox signed left-handed reliever Matt Thornton to a two-year, $12 million extension, with a club option for 2014. Thornton has been with the Sox since 2006, and is set to make $3 million in 2011.

The Thornton acquisition in 2006 is often cited as one of GM Kenny Williams’ greatest coups. Thornton was a pitcher with great potential and a terrific fastball who had never been able to put it together for Seattle. Williams clearly saw some promise, however, as he dealt one-time top Sox prospect Joe Borchard to the M’s. Borchard had only 9 plate appearances for the Mariners before he was quickly claimed off waivers by the Florida Marlins. Since then, he has hit only .215 in the majors, and has been languishing in the minor leagues since the end of 2007. In the meantime, Thornton has become one of the game’s premier lefty relievers, leading the league in K/9 and strikeouts among relievers in 2010, making his first All-Star appearance.

Thornton was plagued with control problems in Seattle, but with the Sox has steadily but drastically cut down his K/BB ratio. Since 2008 his ERA has remained below 3 since emerging as Chicago’s set-up man in 2008. His devastating fastball has proven especially useful against the lefty-heavy lineups of the Minnesota Twins. He stands as joint favorite to win the Sox closer job in 2011. Between Thornton and rookie Chris Sale, the White Sox are in possession of the most powerful lefty bullpen contingent in baseball.

Yes, Thornton is older than you might expect. He was certainly a late bloomer. He’ll have just turned 37 by the end of this two-year deal. And yet he has shown no signs of slowing as he progresses through his 30s. The Sox have been receiving top of the line bullpen help the last few years with minimal financial commitment. Now, Thornton is simply making what he’s worth. And the deal could end up being even better.

2011 was set to be Thornton’s last season with the Sox, and I think it’s fair to say that he would have been in demand on the open market. Hard-throwing lefties out of the pen are a rare commodity, and just about any team in baseball would be interested. Especially if Thornton ends up being Sox closer, he could have been one of the top names of next year’s hot stove. As it is, Sox fans have much reason to celebrate.

Thornton’s come a long way from the man whose departure was celebrated in Seattle.