If NE drafts Bailey, it is my surmise given what little I know about him - and please remember I had him off my board prior to BB giving him the once over, I had absolutely no idea where he would fit or improve this team based on the games I watched last season - that Bailey will be part of the OLB rotation. As a rookie, with hoped for improvement from Cunningham, Ninkovich, and Moore, I wouldn't foresee him taking a lot of critical game reps at anything other than 3rd down sub-rusher and Special Teams. BB has been starting rookies, but for the most part he still prefers to bring them along at a little slower pace.
I only project Bailey to OLB based on his comparison to Cunningham, beyond that I still don't know where BB will or would use him. But with the look NE has had at Clayborn, Bailey, Ballard, etc. there is no way around it, they are looking for "hawgs" to play OLB.