Except it gets tough to rely on any team ever drafting like the Sox did in 2011. That was just a great draft. And Bradley certainly took a long time to get going. Had he not been such an offensive no-show to start his career, the Sox might have never moved Betts to the outfield and very possibly never signed Rusney Castillo.
But more important, these players were already in the farm for the last place finishes. The Sox have no one currently in their farm that such hopes can be pinned on. Certainly a player or two can make some sort of tremendous leap, but you can't count on it. But if you're counting on the future drafts, these two players took 3 years to debut. As dgalehouse points out, the Sox can't afford to starve while waiting for the farm to produce...