Complex sentence: In certain formations, the defense may remove a linebacker or a defensive lineman to bring in extra pass coverage in the form of extra defensthe fifth (extra) defensive back is called a "nickelback" after the U.S. nickel coin, a five-cent piece.
Split into simpler sentences: In certain formations, the defense may remove a linebacker or a defensive lineman to bring in extra pass coverage in the form of extra defensive backs. A formation with five defensive backs is often called a "nickel" formation, and the fifth (extra) defensive back is called a "nickelback" after the U.S. nickel coin, a five-cent piece.