Pablo Sandoval is very solid. I like him almost as much as Donaldson. Sandoval is going to come around in the second half, that big guy in Fenway with the Green Monster out there, now that he's adjusted to the new city he's in he should start getting hot. Even then you're getting a stud centerfielder and a decent replacement for Donaldson.
How many teams are in this league?
I would offer him Donaldson for Sandoval and Adam Jones. You would be killing him in that deal if he does that. And if this is a dynasty league, your team is in good shape. Marte and Rizzo are two great young bats. Then you have Clayton Kershaw, who is having a bit of a rough start but he will get back to his usual self. And Chris Sale. Two ace pitchers on your team. That team, if it's a keeper team, can be at the top by next year.