Well, you need to look at where the team's depth is, and the positions that are set.
5 starting pitchers
1B, 2B, 3B, OF x2
The only positions that will need replacing in the next year or so are SS, bullpen, OF, C, DH and bench. Shortstop should be covered by Lowrie/Iglesias. OF should be covered between Reddick, Kalish, Westmoreland etc. C may be covered by Salty--possibly Martin-- but it is a position that they can be OK with a mediocre player, because there really aren't that many good catchers out there. DH, there are always big bats that can't field who become available every offseason. Bench, same there. Bullpen may be a problem if they don't put money into it.
As far as I'm concerned, the farm has done what it needed to do-- and that is put an elite group of players on the field, with Pedroia, Youk, Bard, Ellsbury, Lester, Buchholz as one of the strongest groups of home-grown players out there, and all of those guys are locked up atleast two more years. All the other holes can be filled-- plus, they'll get as many as 5 first rounders this year to restock.