Chicago Bears

• Defenses are smarter, better, and faster.
• Lack of good QBs. A lot/most of the mid-to-late 2010s QBs haven't turned out well. There was arguably a golden age in the early 2000s of QBs and we're actively feeling "return to normal" part.
• Similar/tangential to the above, lack of good OCs/offensive minds and/or people to execute it.
• There's an arms race in the trenches. There are not a ton of humans that have the frame that supports being a lineman, let alone everything else. The better athletes gravitate towards the flashy/paid roles aka D-Lineman. This leaves the "scraps" to be O-Lineman.

Beyond the above that I feel are pretty easy to verify by a cursory look at year-in-year-out stats, I do think there isn't a great evaluation of collegiate talent nowadays also and hasn't been for a decade or so. I mostly think it's a function of social media or 24hr news cycle or whatever you want to call it to where if a scout, director, GM, or owner wants to fall in love with a decent prospect that also represents a need, it's extremely easy with the amount of highlight reels that're available for any number of people. Tying it back to the Bears, Justin Fields had cameras following him since he was in high school.