Victor Martinez was 5 for 5 with four doubles last night. That will get him a seat on the bench tonight.
But, wait, it makes sense.
The Sox have a day game tomorrow with Tim Wakefield pitching. Martinez needs to catch that game and is playing with that sore left big toe. So that's why Jason Varitek will catch tonight.
Terry Francona just explained it all on WEEI.
In related news, Martinez has not caught Daisuke Matsuzaka since May 17 at Yankee Stadium, when the two had pitch selection issues. But that is a product of Wakefield following Matsuzaka in the rotation as much as anything else.