In 2011, the NFL and the NFLPA signed a new collective bargaining agreement which included a rookie wage scale. One of the many anticipated benefits of the fixed pricing was the elimination of lengthy contract negotiations, which often resulted in highly drafted players holding out into training camp, and in some cases into the season.
The 49ers experienced this phenomena first hand in 2009 when their first round pick, Michael Crabtree, held out well into the season - not signing until the first week of October.
Thankfully the new CBA and rookie wage scale have worked for the most part.