Buffalo Bills v Philadelphia Eagles
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The Philadelphia Eagles opened as 2.5-point home underdogs against the San Francisco 49ers in Sunday's highly-anticipated matchup between two of the best teams in the conference. This is a rematch of the 2023 NFC Championship Game, which the Eagles defeated the 49ers 31-7 in a showdown that wasn't close. 

Haason Reddick knocked out Brock Purdy on the sixth play of the game and the 49ers were forced to play Josh Johnson -- who later was injured by Eagles pressure -- and Christian McCaffrey even lined up at quarterback. With Purdy healthy entering the game, the outcome could be different. 

Of course, Purdy was healthy entering the NFC Championship too. The 49ers are still favored over the Eagles regardless. 

This is the first time a team that entered with a 10-1 record or better will be a home underdog with their normal starting quarterback in the regular season since 1970. This is the same 10-1 Eagles team that has started 10-1 or better in consecutive seasons, the first team to accomplish this since the 2005-2006 Indianapolis Colts

There have only been two other instances where a team that's 10-1 or better has been a home underdog, and those teams were resting starters. The 2011 Green Bay Packers and 2020 Kansas City Chiefs, were both resting starters in the final week of the regular season. The Packers won by four and the Chiefs lost by 17. 

So why are the Eagles home underdogs even though they have the best record in the NFL by two games and beat the 49ers last year? 

Brock Purdy's injury

Purdy tore his UCL in the first quarter of the NFC Championship Game loss, a factor that was considered heading into this matchup. This isn't implying the outcome would have been different if Purdy was able to stay healthy, but perhaps the game would have been more competitive. 

Purdy does lead the NFL in completion percentage (70.2%), yards per attempt (9.4), and passer rating (12.3). He also has been the favorite in all of his 16 starts, setting an NFL record since the merger. The 49ers are a different team in games Purdy starts and finishes, going 14-3 in those games. 

Eagles have been the comeback kids

While the Eagles are beating the good teams on their schedule (4-0 against teams with winning records), their last four wins have been in come-from-behind fashion. The Eagles are the first team in NFL history to win their first four games of a season when trailing by 10-plus points and their the fourth team in NFL history to win four straight games -- all when trailing at halftime.

Jalen Hurts has eight straight wins with play run after trailing by 10-plus points -- double any other quarterback streak since at least 1991 (the play-by-play tracking era started). Whether this can sustain or not will be decided, but Philadelphia has a two-game lead on the rest of the NFC. 

The Eagles don't have to apologize to anyone how they're winning games, but Vegas is taking notice. Philadelphia's +64 point differential is the second-lowest for a team 10-1 or better through 11 games, as only the 1976 Oakland Raiders are worse (they won the Super Bowl). 

49ers have been dominant of late 

The 49ers are 3-0 since the bye week, averaging 30.7 points per game and allowing just 10.0 points per game with a plus-7 turnover differential. San Francisco's pass rush has been dominant since acquiring Chase Young, having a 61% pressure rate and 15% sack rate. No quarterback has thrown a touchdown pass against the 49ers since Young arrived, as opposing quarterbacks have a 56.4 passer rating in three games with Young. 

Nick Bosa has 22 pressures and Arik Armstead has 16 since Young arrived, as his presence has significantly helped the 49ers' front. Doesn't matter who the 49ers have faced, they are beating teams convincingly. Their pass rush has a lot to do with those convincing wins.