[Defensewins]

THis quote from the article says it all:
"Bellichick’s philosophy was (and always has been) the 3-4 defense, but he didn’t implement it until 2003 when he acquired all the right pieces. "
They won their first Sb in 2000-2001 with the 4-3. A defense Bellichick historically was not accustomed to playing as his base. But he looked at his roster and wisely decided to implement the 4-3 because that is what his roster could run best. Even though he always intended to go back to the 3-4 once he had the right pieces. Bellichick put his large ego aside to do what was best for the team and winning at the time.
This is a part of the mistakes our coaching staff made in 2010.

The above article incorrectly tries to imply that if you switch to the 3-4, it is like a magic pill that over time will make your defense better. NO.
If History tells us one thing is football is an ever changing sport strategically. What scheme works best yesterday will not work as well today or tomorrow, because coaches and players learn ways to counter it. The 4-3 dominated like no other defense before it in the 60' through late 90's. The 3-4 was run over during that time in the Super Bowl big game. Embarrassing.
Now 3-4 has made a huge come back. Great. But over time that will eventually change as well.
In order to have a great defense or team you have to have the talented players and coaches to run it correctly. Thank you Vinny and Snyder! Regardless of scheme if you do not have the horses, especially up front, you will get killed. The great defense do not have any weakness (players) that can be picked on. FO and player personnel is as or more important than any single scheme. The great teams have the great players and talent.
The Bills and the Redskins were not bad teams because we ran the 4-3. We were bad because we had mostly players that were not great.