I am not sure how they could get much less than an A.
They signed one 4 of arguably the top 20, and almost certainly top 30 free agents in KG, Bass, Green, and Terry. Even Lee has a case for the top 30 as well.
They filled basically every hole they have.
And in the draft, they got a major slider in Sullinger.
On paper, I am not sure how the summer could have been much better, given what they had to work with.