Okay, from a keeper standpoint, Wells, Danks are of little consequence here. A-ROD probably has 2 more years as a top tier 3B, then a couple more as a 2nd or 3rd tier. Frese will not hit for power and long term that will drive you nuts since he plays a power position. Boesch is unproven, Papelbon is replaceable. Lackey, on the otherhand, is a money pitcher.
So here it is - veteran ARod for veterans Lackey, Papelbon - advantage you. Danks and Wells - can help some this year, but long term - who knows Boesch and Frese are both wild cards, and it's not like you're giving up Heyward and Strasburg.
I'd do it. There will be another Boesch and another Frese next year, and the year after that. How many shots do you get at picking up ARod?