My guess is this tidbit from the article is crucially important.
Torres, Acosta, Gladney, Glass, Trenkle and Krogman are all going to cost extra money, whereas if the Sox took Allan, they'd have maybe been able to sneak in one of those guys.
So far they've got Gladney and Glass. But right now they have a chance to add 8 high schoolers to the system, which I think would have seemed unfathomable a year ago.