I'd replace Lowrie with Lugo, because he's not going to be back when Ortiz is back. I also expect Ellsbury to continue to bat at the top of the lineup. Not that it's the correct choice.
To add, the rotation features four pitchers with ERA's under 4.00, and the combo of Masterson, Colon, Pauley, and Buchholz has added a 4.01 ERA.
Masterson is going to be a big arm out of the pen, and Colon can help as well. That's not even mentioning the fact that the Red Sox can go add another arm with that deep farm system at their disposal.
This is shaping up to be a good second half.