Butler was benched for Rowe who played pretty well. Richards, who everyone blames for the loss, was the nickel or slot corner and that's not a position Butler played at all over the course of the season. While Butler is a solid tackler and would have helped in that regard it's not as simple as saying "Oh they would have won with him in there."
Butler was also terrible against JAX two weeks earlier and apparently didn't have his shit together enough to warrant getting playing time in the SB.
I mean, we won another the next year. It's time to get over it. Philly played like shit on D too.
Brady: 28-48, 505 yds, 3 td, 0 int
Foles: 28-43, 373 yds, 3 td, 1 int
TOT: 56-91 (61.5%), 878 yds, 6 td, 1 int
One of the main reasons for this was because they called zero offensive holding penalties on passing plays. Not one. And holy crap there were a ton they could have called. That meant that both QBs threw with tons of time. Only one sack all night long - by Graham at the end that caused the Brady fumble. That's it.
And yes it makes a huge difference. Compare this year to last year:
2019: 63.5%, 7.2 y/a, 90.4 rating - 582 off holding penalties in 256 games played (2.27 per game)
2020: 65.7%, 7.3 y/a, 94.6 rating - 215 off holding penalties in 146 games played (1.47 per game)
The defenses weren't as bad as they looked in that Super Bowl. They weren't very good, and both QBs were phenomenal, but the lack of holding penalties impacted the game big-time.