Dump the manager, keep the regulars, and get one good arm and and one or two good bats for OF/1B. That means not trading Ells and re-signing Ortiz and Ross.
The details on getting those good arm and bats are not simple, but should be doable.
Ells stays because CC is gone, making Ells affordable (though he may still leave) and because Ells very much needs another good year. Ortiz and Ross stay because the Sox now need hitting. Keeping Pedroia, Middlebrooks, and Salty/Lavarnway--obvious. A good bat at 1B looks pretty important right now--AGon was a big loss. And another one in the OF would be nice.