Well, in all fairness, the nucleus and most of the supporting cast was intact into late 04 and 05. Yes, Cabrera was new but he fit in perfectly, Mientkiewicz wasn't a starter, and Robert's fit in well and also was a role-player. On the chemistry factor I believe it is a factor if you look at history. I mean the Yanks of the 1990's had been together for more than a couple of years and meshed in really well with their style of play.
However this doesn't mean that this is a bad move, because as I stated earlier this off-season this is still somewhat of a transistion period from the 04 team to submitting rookies into everyday roles. Lester, Papelbon, Beckett, Hansen, Pedroia, and eventually Ellsbury will be a very stable and solid core if they all make it up and fulfill their potential. And they all share the same style of dirtdog, ice-water in the veins type play.