I think it was Goose who said that at 51 we should be able to get a quality Safety.
IMO, at 51 we could get a good Safety or a solid interior OL - esp Center position.
As for WR, I think the top 7 or so, including Robiskie, will be gone by 51. I think there will be better value in the 3rd or 4th for WR.
From our perspective, we just happen to need depth at Safety, so just sitting at 51 could be advantageous for us.