BOSTON n Sean Casey knew coming to the Red Sox would be a trade-off: A chance to be on a winning team and go to the play-offs vs. a starting job. Casey n a three-time All-Star, .301 career hitter, and starter throughout his 12-year career n chose the team over the starting job.And that was fine with him.?At this stage of my career, I don?t know if it?s about individual stats,” Casey said in spring training. “And after being in Detroit and realizing what it?s like to be on a winning team and play in a World Series and what it?s like to be in that environment, I think it kind of changes how you feel about things.”Casey was the starting first baseman on the Tigers team that went to the World Series in 2006, losing to the Cardinals in five games.With third baseman Mike Lowell on the 15-day disabled list with a sprained left thumb n which could potentially keep him out longer than 15 days n Casey finds himself, for the time being, a regular part of the lineup. Kevin Youkilis has moved across the diamond to take over third base duties with Casey taking over at first.Lowell, who injured his thumb on the first play of Thursday?s game against the Tigers, diving for Ivan Rodriguez?s liner, came out of the game before his first at-bat, with Casey pinch-hitting for him.?It is definitely weird,” Casey, 33, said of adjusting to coming in off the bench. “I was like, I got my jacket on, sitting there. (Jason) Varitek came up and said, ?Hey, I just want to give you a heads up. Mikey might have hurt his thumb.? And I started this instant sweating, just an adrenaline rush. I?m like, ?Oh, my God!? So, I go downstairs. Mike?s in the tunnel. I can see he takes a couple of swings, and was like, ?Ow.? So I said, ?OK, get ready to go in.? So, then he goes out to the field, Mikey?s on deck, and I?m kind of starting to get ready. (Manager Terry Francona) Tito?s like, ?We got action. You?re on deck.? And I?m like, ?I am?!” So it?s definitely a different animal coming in like that.”Casey entered the season with no specific number of at-bats in mind, accepting that he likely would not get the 500 at-bats he is accustomed to.?I just came in thinking funny things happen in this game sometimes,” he said. “I just came in really trying to be on a winning team and trying to be a part of it really, and do whatever I needed to do. I knew I wasn?t coming in to be a starter, but this is the first time in my career I haven?t had that. So it?s an adjustment mentally. But, I knew what I was coming into. And it seemed like this was one of those situations if something ever did happen with Mikey or ?Youk,? I?d be able to fill in.”Since filling in for Lowell, Casey has gone 4-for-13, hitting. 308 with four RBI. After going 2-for-3 with a run scored and an RBI in the Sox?s win over the Yankees last night, Casey is hitting .318 (7-for-22) with five RBI in seven games this season.?I think it?s just whenever we get Mikey back and I?ll hold the fort down till then, I hope,” he said. “I?m sure I?ll be part of the equation of this club all year long. I think we?re all really looking forward to getting Mike back.”