Agree with Oldtimer1.
As he noted, band training can have a major role in strengthening the four muscle attachments of the rotator cuff it's self, even considering that style training before DB work. In any event, try keeping the area warm when working the rotator cuff region, increasing the blood supply to the area is important (a heat pad, lotion, etc).
Flexibility (or lack of it) of the shoulder girdle has a strong influence on the rotator cuff. Even the flexibility of the spine (bad posture/alinement, etc) comes into play. Good Luck