The defensive end has multiple assignments and alignments for every play. You’ve got to be able to set the edge, read the man in front of you and defend several different types of blocks.
For instance, when the offensive lineman moves away from you, you want to engage the lineman, but stay square to the line of scrimmage, looking to see if another lineman — a fullback or even the quarterback on a read — is coming your way. If it is a blocker, throw your outside arm into them, cutting in front of them to prevent the running back from getting to the hole.
When the offensive lineman steps toward your outside shoulder, however, you want to engage with them and work your feet to stay outside while keeping your outside arm and shoulder free.
A third read for a defensive end is the base block. In the base block, the offensive lineman steps straight at you. Engage and extend your arms, driving the offensive lineman back to create a new line of scrimmage. At the same time, watch to see which side the running back is heading, so you can be prepared to escape the block and make a tackle.
By reading the movements of the offensive lineman, a defensive end will be able to better understand the play call and adjust his own movements to disrupt the running back.