The theory is universal for any bust though, you have to look beyond the physical measurables.
Michael Huff has shown up EVERY season out of shape. This is a first round pick making 6 figured with a 7 figure signing bonus who does not even take his "job" seriously enough to show up in shape for camp. This is not a system or coaching deficiency, it is a player not caring.
Randy Moss proved himself BEFORE going to the Raiders, got traded to an awful team so he didn't try for two years, then tried again when he was with the Pats. It's not like he was a terrible player who came to life only after leaving the raiders. Alex Smith on the same hand has outplayed Russell in every category despite different OC's and coaches every year.
And regardless of OL, it's hard to be effective when you're always injured like McFadden. We could say Jerome McDougle could have been a good player his first few years, but it doesn't matter cause dude was always hurt.
You also have to keep in mind that QB, WR, RB, and DB are all the easiest positions to excel at in college, and then fail in at the NFL Level. In College, if a RB or WR is fast enough, talent like route running, D-reading, etc become less important. For a QB, college offenses are so drastically different (usually involving much more shotgun and option style plays) that the first question asked of ANY college QB is how he will translate to reading NFL Defenses, taking snaps under center, etc. With DB's, the speed factor is also there in that if you are fast enough you can succeed in college, or if you hit hard enough. The whole thing is, only 250 kids get drafted every year, say another 250-350 go in as UDFAs. That's 500-600 Juniors and Seniors who were playing against the other multpile thousands of kids who were either underclassmen or simply not good enough to be in the NFL. So being good in college does not always mean you'll be good in the NFL.
50% of first-round picks bust, it's a proven fact. Not all of those busts (and I'd even argue less than half of them) are so simply because of bad coaching. These kids (mostly) grew up poor and always doing whatever they wanted because of their god-given ability. They get to the NFL, suddenly have more money than they've ever imagined, and have to live under strict dietary and workout regimens, have their every action scrutinized by coaches, players, and the media, and they have coaches and owners with WAY more power than anyone they've ever played for before. It's a total shock to their lives. Then there are the people like Albert Haynesworth in terms of mentality. They will have all the physical gifts imaginable, yet they just do not care enough about football. Haynesworth was able to play 2 good years of dominant ball to fool the league, then he got paid, and stopped caring again. Some college kids fail their rookie combine drug tests. How ridiculous is that? Sure, do drugs, but when you know you have a drug test coming up that is going to determine whether you make seven figures playing a game, or you go into the real world and work for a living, it should not be too hard to get clean. Yet some kids still fail. The bottom line is not everyone who is good enough to play in the NFL necessarily WANTS to, so it's not always just a case of bad coaching, some kids just took their money and ran.