When a player who was first round pick fails in the NFL, we call him a "bust". I don't really like to use the word "bust".
Some players just don't develop well when they sit behind other players. If they get time on the field, they can develop quicker...sometimes. If you put players on an NFL field they could get injured, then they could make mistakes, and lose their confidence.
Kurt Warner, Warren Moon, Jeff Garcia,Joe Thiesmann, and Joe Horn, did not start their careers in the NFL. Kurt Warner went to the Arena Football League and he will tell you that the AFL helped him alot in the NFL.
The rest of them began their careers in the CFL. I don't know if they would tell you that the CFL helped them become great players in the NFL, but I think playing in a pass heavy league and playing on a bigger field helped them a lot.
The guys that I named (with the exception of Joe Horn) weren't even drafted. Going to a league where you can develop doesn't just help the ones that were drafted in the first round, but it also helps the late rounders and the undrafted free agents.
Jamarcus Russel was a guy who was thrown into a situation too soon. If he had went somewhere to develop his game, maybe things would have turned out differently for Russel.
I doubt Tim Tebow will be even a decent quarterback in the NFL. He played in the spread offense and quarterbacks that play in that system usually don't do too well. I think instead of sitting Tebow on the bench and letting him watch Quinn & Orton, it would be good for Tebow to play in a developmental league and work on becoming a pocket passer in the NFL. If he could do that then maybe....just maybe... he can be a really good quarterback.
The NFL got rid of NFL Europe because it was the best move financially. So going for another developmental league might be a risk, but if the NFL wants to at least try to avoid having players playing terribly because of not being developed the proper way then maybe it is a risk that they need to take.
For once the NFL needs to try to do something that will benefit all the young players.