What causes college studs to become busts in the NFL?

Here are some examples: Cade McNown, Akili Smith, Tim Couch and Ryan Leaf.

What causescollegestuds to become busts in the NFL?nba gear

Some players are products of their system (Andre Ware, Ty Detmer). If you're team throws the ball 60 times a game, of course you've got good passing numbers. But if you've never seen a complex defense in college, like Andre Ware, the NFL is a rude-awakening. That's why Matt Leinart was called "the best prepared QB in the draft", because he played in a pro style offense and saw complex defenses in the Pac-10.

Ryan Leaf was a head-case and San Diego didn't put anybody around him anyway. Tim Couch also, it's not like the Browns had a great front office to support him.

What causescollegestuds to become busts in the NFL?nba finals 2007 ,nba teams

ummm...because in the Pros you face real teams with real players every single game. For example you cant schedule a dozen creampuffs...like OSU did this year. Even the worst NFL team would beat the bestcollegeteam...cause ALL NFL teams are made up of the absolute bestcollegeplayers.
Hype. They are overrated to begin with.
well sometimes they are thrown into NFL play when they arent ready and are expected to turn a losing team around, its really unfair....or they just arent NFL good, there is a huge difference betweencollegegood and NFL good, incollegeyou play against guys that might make it to the NFL, in the NFL, you are playing against the elite football players, and their ability isnt up to par
The NFL is MUCH faster and MUCH stronger and MUCH harder than thecollegegame. only true stars can be successful in the nfl
Overrated, attitude, hype, etc. Somecollegeplayers just can't make the transition or handle the pressure in the pros as well as other players.
There are hundreds of things that can do it. Some of the biggest are, too much hype, lower level of competition, scheme players who don't fit into the nfl style, too much pressure, undersized, injury prone, bad attitude, and unwilling to work hard. The last one being the biggest in my mind.