Now, this doesn't mean you should trade Ellis Burks - he'll be very productive when he's in the lineup. But, you can count on him spending some time on the disabled list this season. You need to be prepared with a good backup. For me, I'm counting on Larry Walker missing some time - he always does. In general, my advice is to set your lineup of hitters and stay with it barring injury.
Hitters tend to be pretty consistent.
Chances are that Goodwin's numbers for the week will be as good or better than Bergeron, and you'll kick yourself if you start manipulating your lineup like that. Sure, if you've got a player with an injury you take him out, or if you've got a platoon player who sits against lefties, and the team is scheduled to face 2 or 3 lefty starters this week, you might make a move. But don't try to monkey with your hitters much. Pick your best guys and stick with them. You'll be sure to catch the hot games as well as the cold games and at the end of the season they will give you the stats that you expect.