The Pre-season and the lockout.

[Ruhskins]

Originally Posted by Longtimefan

Aside from any lost revenue as a result of this protracted lockout, these are the guys who will suffer the most where the game itself is concerned. With limited time to impress the coaches and comprehend a complicated system true talents in some cases will not have enough time to be put on display.

Don’t expect too much from Redskins’ rookies too soon - The Insider - The Washington Post

I would add to this that the quality of football is going to suffer as well, especially with teams that will have new coaches and a significant amount of new players (rookies, FA, etc., etc.).