Patrick Mahomes and the Kansas City Chiefs are favored to notch the NFL’s first Super Bowl Era three-peat Sunday in New Orleans. But entering Super Bowl 59 as a sportsbook-consensus 1.5-point underdog actually could portend good things for the Philadelphia Eagles. We explain below with an analysis of underdogs in the Big Game and how they’ve been on eye-catching roll since the turn of the century. Regardless, though, of which side you like in Super Bowl 59, be sure to take advantage of our top online sports betting promo offers, which currently are worth nearly $4,000 in new customer welcome bonuses. Favorites dominated early, often on Super stage In the first 3-plus decades of the Super Bowl, spanning the 1966 through 2000 seasons, Big Game point spread favorites ran roughshod.  They won 27 of the 35 games outright for a .771 winning percentage while compiling an impressive 22-11-2 record (.657) against the spread. It was an era of dynasties and powerhouses as the Dallas Cowboys and San Francisco 49ers each claimed five Lombardi Trophies during that span while the Pittsburgh Steelers won four titles and the Green Bay Packers, Oakland/Los Angeles Raiders and Washington Redskins notched three apiece. A full 25 of those first 35 Super Bowls featured double-digit margins of victory, including eight of the 10 most lopsided matchups in Big Game history. The Lines Podcast: Eli Hershkovich and Evan Silva Make Their Expert Super Bowl 59 Picks Underdogs have displayed serious bite since 2001 There’s been quite the reversal of fortune, though, over the last 23 Super Bowls. Since 2001, Big Game favorites have gone only 10-13 (.435) straight-up. And they’ve fared even worse against the spread with an unsightly 6-17 (.261) record. With the underdog Chiefs’ 25-22 victory over the favored 49ers last February, ’dogs have covered in four straight Super Bowls (3-1 SU) and 10 of the last 13 (9-4 SU). The number of one-sided games has dwindled as well during that span with only nine of those 23 Super Bowls being decided by double digits. Breaking down the numbers, trends for Eagles, Chiefs Kansas City is playing in its fifth Super Bowl in the last six seasons, going 3-1 SU and ATS in those previous four appearances. That includes a 38-35 victory over the 2-point favorite Eagles two years ago in Super Bowl 58. This season, including a pair of home playoff wins, the Chiefs are 17-2 SU but are only 9-10 ATS in those games. Philly, meanwhile, beings 17-3 SU and 13-7 ATS marks into SB59, including a trio of home playoff victories (2-1 ATS). Mahomes and Co., have gone 16-0 SU and 8-9 ATS as a favorite in 2024-25 but are 6-0  when laying 3.5 points or fewer. As underdogs this season, the Eagles are 3-0 SU and ATS. So what will be come Super Sunday Night in the Big Easy: A historic Super Bowl-era three-peat for the Chiefs or the Eagles becoming the fifth consecutive Big Game underdog to cover?