Elway actually played well in his first Superbowl in 1986 against the Giants. A 59.5% completion percentage, 304 yards, 8.2 YPA, 1 TD and 1 INT for a 83.6 QB rating. His next two Superbowls QB ratings were 36.8 and 19.4.
He didn't play as great as many would like to remember when he and the Broncos finally won it all against Green Bay. Completed only 12 of 22(54.5%) passes for 123 yards(5.2 YPA), 0 TDs and 1 INT for a rating of 51.9. Everyone remembers him diving and flipping in the air, which was impressive. The rest of his game was not. The O-line and Terrell Davis' running carried that team in that game.
Elway had a very good game against Atlanta.