Clubhouse guru and media relations darling Sean Casey is coming to play for the Red Sox on an unguaranteed one year, $700,000 contract according to ESPN.com.  It seems likely that Casey will back up Kevin Youkilis at first base and will be available to come off the bench when the Sox need a left-handed bat for pinch hit duty.  Casey will also come in handy when Mike Lowell needs a day off, as Youk can slide over to third and Casey can grab first.  "The Mayor" has a .301 career batting average.