see linked ND Observer article...scroll to page 4...Tony Capers injury explained.
Reporter Terry O'Neil ( later a famous producer on ABC's Monday Night Football) claimed the Capers injury happened as followed
Capers was in playing defense end...Oklahoma RB Steve Owens(later a Heisman winner) tries to block Tony on a Sooner sweep around DE Capers- but 'misses'...'scrambles on the ground' a few yards & attempts to 'leg whip' Capers in order to take Tony out of the play...misses(again)...but his cleat clips Capers Achilles tendon...snapping the tendon.....Tony Capers season was over