I have a hypothesis that many of the high picks who bust are pretty much a function of work ethic/character issues, environment, and often both. Unless you're just a completely rare athlete with preternatural feel for the game you're never going to be elite in the NFL unless you have the requisite work ethic/character/demeanor/whatever you want to call it.
The environment a player goes into into, the coaches they have, and especially the plan a team has for them when they're drafted are also major factors. If a 4-3 team took Watt a few years ago and asked him to put his hand down and go stop the run heads up on an island vs. OT's all game he probably wouldn't have been very successful. Same for a guy like Baun and Chaisson this year.
If a team takes Ruggs and asks him to go line up as a static X WR all game, beat press, and beat CB's running comebacks and slants he probably isn't going to be very effective.
Look at a guy like Charlton. I don't think he had his head screwed on right and/or couldn't take the pressure of being a number 1 pick, had a falling out with the staff, sulked, and got cut. Would a guy like DeMarcus Ware be DeMarcus Ware if he had the same mindset/demeanor?
Probably not.
And even then he goes to Miami and puts up 5 sacks in 10 games once he's in a new environment. Even if he lucked into a few of those that's still on pace for 8 sacks after getting cut mid-season.
Byron Jones is another great example. He goes from maybe an above average safety over his first 3 years to becoming the highest paid CB in the league 2 years later once he fell into a scheme that accentuated his abilities. Would that have happened if we never hired Richard/went to almost strictly Cover-3?
Doubtful.
All of that is a very long-winded way of saying that often we have no idea why a player busts and/or there are multiple very impactful factors at play that could've resulted in very different outcomes had they been different.