A basic 4-3 defense consists of 4 Down linemen and 3 Linebackers. This is a classic formation against the run. There are two Cornerbacks and two Safetys to cover the pass plays. If an offense has a good pass catching TE, it can take advantage of the slow speed of linebackers. The middle would be open for the QB to throw passes to TE.
Talking about linebackers, how many great linebackers are in the game? Ray Lewis even past his prime, is playing amazingly well this year. Him and Peyton Manning are the smartest player in the league, very hard to trick them. Manning read the Steelers blitzes perfectly and 3 years ago he could not. Thanks to his study habits, he was able to dissect the blitzes.