I think if Bloom makes a big trade, he tries to minimize what he gives up and/or maximize his return by taking back a bad (but potentially useful) contract, much like he tried with Wil Myers last offseason.
Some contracts that might make sense for the Sox to take on along with a SP include Kevin Kiermaier (2 yrs $25.6 mill), Ender Inciarte (1 yr $9.7 mill), Lorenzo Cain (2 yrs $35 mill) or Rougned Odor (2 yrs $27.6 mill), and I suppose Myers should still be on the list. So see what pitchers Tampa, Atlanta, Milwaukee, Texas and San Diego still have they might be happy moving in order to save a lot of money...