I don't think it's the WR's can't get separation. I think it's a lack of imagination and creativity that is making it easier to guard predictable routes by the WR's.Bad OL. No running game. WR's that can't get separation. Rodgers old and now injured.
Rodgers also needs to get out of his comfort zone with the receivers and start trusting them to make plays. 70% of the throws to Lazard, should be going to Williams. He is a much better receiver and isn't going to drop balls the way Lazard does (and the droppies have been an issue with him since GB, so that will never change).