Basically, to have a shot in the NFL right now you need a good-great QB on a rookie contract that gives the team enough cap space to go get other players. As soon as the QB gets paid, the team starts to feel the squeeze and that's been a problem for years.
A lot of teams try to pick a QB first and then build around him because QBs go so high in the draft that it's hard to get one if you're not picking in the top 10. The Bears have been a QB away for a long time, but as things stand they're too good to get a really high pick - so all the building they've done in other areas will go to waste if they can't find their QB soon.