I'm often puzzled at these premise-based questions. Not just "why isn't this on the advice board" (putting "official" in the topic title doesn't make it not a "help" topic), but more specifically why would Brown fall to you at 4 as you assert as your premise? If I'm at 3 and DJ/Bell are gone, Brown is my easy pick at 1.03 - IMO the clear cut WR1, Looking at ADP that seems to be consistent with most in the FFB world for PPR, 1/2 PPR and non-PPR.
With a high ankle sprain I've bumped ODB down quite a bit, but I was already lower on him than many already for my own reasons, so the injury just makes it easier for me to pass & grab Julio. So if you're going WR, Julio is the next best, and maybe Evans or Green next (I see that as a coin flip, but many prefer Evans). If RB, McCoy seems like an obvious pick at 4, but if he goes at 3, and you're bent on a RB, Gordon is next up. That's pretty straightforward.
As for the later rounds, discussing who you
should pick there is a bit silly, since no one knows who's going to be there. All you know is ADP, and it's up to you to rank these players in the order you would take them if they're there. If only one makes it there, boom - there's your pick. If several make it there, that's what your pre-draft rankings are for.
Don't take ARod in the 2nd round. Let someone else reach for a QB. Or hey, it's your draft - take ODB 1.04 & Zeke 2.09 and go up to the 1st 6 games without both, then 1 of your top two players. I hear that's a key to success in some leagues.

(note: heavy sarcasm, not real advice in that last sentence)