re: Based on what you've seen of the defense so far this year, which positions

PRob is done and Greer is getting up there in age. CB should be our priority on defense. Don't forget that we're getting back Butler next season. At worst, I think he'll be an adequate 1 year stop gap that would allow us put off drafting an OLB/DE for another year. I'd put the order in terms of biggest need as:
CB
S
ILB
OLB

Looks like a deep draft for CB as well. I'd put OL as the top need, though. You can usually get a top 3 C in the draft in the late 2nd/early 3rd, so that's where I'd focus on getting one, hopefully re-signing DLP to be a very good backup to LG/C/RG.