Offensive/defensive formation tutorials?

[markprior22]

Are there any sites that have brief descriptions of the various formations used in Madden (free sites I might add)? I am a "football fan" but don't have the X and O knowledge that some of you do. I like to play the game but I often feel that I'm picking plays for no rhyme or reason. I know about blitzing, double covering receivers and that kind of stuff. What I'm not so sure about are things like "what is a cover 2 good against, what is velcro defense" and that sort of thing. A little offensive explanation would be helpful but it is mostly the defensive packages that I struggle with. I don't want a cheat manual or anything like that...just want to get a little more in depth without turning it into rocket science.

Thanks