The Packers just haven't seemed to be as good at developing WRs since they lost WR coach Jimmy Robinson (who was going to retire, until his best friend became the head coach for the Cowboys).
But the Packers just plain haven't been that good at drafting defensive players... so many wasted picks on busts or under preformers on the DL/OLB, and Shields and Williams have been some of their best CBs, and they were UDFAs.
This is what happens when you struggle at drafting and developing players.
Of course the draft is partly a crap shoot. You can make a lot of right calls, and the players just might not develop for some reason, like Spriggs, who seems to have all the physical talent, but sure didn't play like it and might of gotten worse since his rookie year.
Though, there still aren't yet enough pieces, especially at the important positions of CB and OLB, but the current defense is starting to seem like it could become the Packers deepest in terms of talent since their last Super Bowl in another year or two. Just need DT Adams to develop, and more/better OLB/CB play on defense.
On offense, they really need a #1 WR to step up, or at minimum a deep threat. Nelson still got it with his connect with Rodgers, but I don't think he has that connection with Hundley, but Nelson is getting older and slower. I'm not sure Cobb nor Adams have it to be the top guy. And they need their OL to stay healthy.