Rauch has bounced around quite a bit over the past few years, but he spent the 2011 season with the Toronto Blue Jays, earning $3.5 million in the process. Toronto held a club option for the 2012 season at $3.75 million but chose to decline it, paying Rauch a $250,000 buyout instead.
After pretty good years in 2009 and 2010, Rauch struggled mightily in 2011, which explains why the Blue Jays decided to seek alternatives in their bullpen. His 4.85 ERA was by far the worst of any single season in his career, but an xFIP of 4.56 suggests that he may have been at least a little bit unlucky in terms of giving up home runs.
On the upside, Rauch is pretty stingy with the free passes. Over the past three seasons, he's walked only 2.55 batters per nine innings, which isn't elite but is still pretty good. It's a lot better than the rates of the Mets' bullpen this year.
Sandy Alderson made it known at the end of the season that one of his top priorities was intelligently improving the bullpen. Rauch may end up closing games for the Mets, but it wouldn't be surprising for the team to sign another reliever or two over the coming days and weeks.