King of the Wolfies said:
The NFL owners can move the trade date back. The reason I heard they wont do it is because they believe a player takes a month to become acclimated to their new team. Thats why we rarely see any mid season trades and when we do, its usually for backups.

People always compare Football to Baseball. They're not the least bit alike. In Baseball, whether you're playing for the Toronto Bluejays or the Tampa Bay Devil Rays, you're going to see the same pitches. You're going to throw the ball to the exact same base as you always do in that situation. You catch and throw the ball exactly the same. Hitting is the same, running is the same, stealing is the same, bunting is the same, a ball is still a ball, and a strike is still a strike. As a result, the players are a lot more interchangeable. You could take every single player in MLB and put them into a player pool, have every team redraft their entire franchise, and then play ballgames the very next day. In football, you could pit a pro-bowl team with no practice time against the Miami Dolphins and the Dolphins would win, because the Dolphins have a playbook, they have blocking schemes, they know their progressions, and they know their depth chart and their pecking order. The pro-bowl team would just be playing a disorganized sandlot mess, and would get killed.You can move the trade deadline to the day before the superbowl, but unless a player actually has a training camp to learn the schemes, he's probably not going to wind up contributing to the team outside of emergency situations or extremely specialized packages. Why do you think Byron Leftwich was out on the street for almost 2 weeks? Teams wouldn't have had to give up ANYTHING to acquire Leftwich, who at the very, very worst is an upgrade over all 32 backup QBs in the league, and yet he sat out for two weeks with no offers, with no team even flying him in for a physical. Imagine if teams would have had to actually trade something to get him.