1991 was definitely still the junk wax era, and the junk wax had expanded with Topps, Donruss, Fleer, and Upper Deck all releasing products that year. That, coupled with a number of busts in recent years for prospectors (Brien Taylor and Todd Van Poppel come to mind) left a lot to be desired in the industry. Donruss had a set for a number of years in their product called Diamond Kings, with artistic renderings of star players on the card. In 1991 they introduced Elite Series, a chase insert set with a high gloss finish and gold edges. Cards were mostly numbered to 10k cards, which seems silly now, but was considered an insane short print then.
Out of that came a single card shorter print card. It was an autographed card of Ryne Sandberg. The concept was almost unprecedented, adding such a chase element to baseball cards. After that, inserts and autographs started to become synonymous with pack opening.
Random Ryne Sandberg Fact: Sandberg was drafted in the 20th round of the 1978 MLB draft. From everyone drafted in that round that year, they had a total of 8390 MLB at bats. Sandberg was responsible for 8385 of them.