Not only might they go D at 37, I think that OLB has a bigger priority than CB.
Barwin is older and Quinn has injury issues and a huge contract. If they got a starting quality OLB, after 2017 they could replace Quinn and save $11 mil in cap space.
Not only that, they really have nothing behind Quinn and Barwin.
They have starters and depth at CB.
But, in the end, I think the board itself will dictate the pick and whatever player is graded highest will be their choice.....with the exception of QB and RB and perhaps DT.