The point --------
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The Red Sox wanted to get younger and better at the same time. So, they made trades (Pena, Beckett and Crisp), and worked some of their prospects into the lineup (Papelbon, Lester, Hansen, Youkilis, and Delcarmen) while holding onto the other blue-chip ones. In other words, they'll make the team better, but not at the cost of a blue-chipper.
Call it, prospect holding.