There is no question that the Sox needed another big bat in this lineup. But if Cora keeps playing JD in the Fenway Park OF it is only a matter of time before JD gets Swiharted out there (meaning a less than adequate fielder put into what is likely the most physically dangerous OF in all baseball, our beloved Fenway Park OF). When that happens, that big bat will be stuck in rehab for God only knows how long.
Play JD in the field away from Fenway if you must. At least away from Fenway you just take a hit to your overall defense. You don't take the hit to your defense and run the additional physical risk presented by the Fenway OF. Honestly JD looks like a dead man walking out there. More aptly put, he looks like Nunny looks around 2nd base. But at least away from Fenway there is way less chance of JD running smack into an injury. DH JD in Fenway and play him in the field away from Fenway a few games per road trip.