There's no mystery that Malcolm Butler's interception was the most valuable play of the Super Bowl. It sealed the victory for New England and secured the franchise's fourth Super Bowl title.
The advanced stats agree. According to Pro Football Reference's expected points model, Seattle's possession of the ball on the 5 yard line with 1 minute left in the game was worth an expected value of 6.1 points. Essentially, historical data shows that teams in the Seahawks situation average nearly a touchdown as a result. Seattle's winning percentage was 84.4% prior to the interception, and fell to 0.2% after.
It was magical and it was probably the most valuable play in NFL history. It wasn't a unique situation- there've been a handful of last minute red zone turnovers on the goal line in one score games, including one where Peyton Manning's defense forced a goal line turnover while down three points in the playoffs, only for an idiot kicker to miss a field goal after a quality drive by the Colts offense. The only goal line play with the same win percentage shift came in a Week 14 game with Joe Webb at quarterback- not the same.
Beyond that tremendous game changing play by Butler, there were plenty of other plays that managed to swing the game in one direction or another.
Tom Brady's red zone interception by Jeremy Lane cost New England an expected 3.5 points. His touchdown pass to Rob Gronkowski on second down was worth 3.1 points. Brady's third down coversions to Julian Edelman on the team's first 4th quarter scoring drives were worth 2.9 and 3.5 points, respectively.
Russell Wilson had his own plays outside of the -5.5 point goal line interception- note: it wasn't worth -6.1 because Marshawn Lynch's 4 yard run was worth -0.2 expected points for the Seahawks after the clock ran down, and the Patriots had -0.4 expected points with the ball on the goal line due to safeties and other mishaps.
Wilson's 44-yard and 45-yard passes to Chris Matthews were worth an expected 3.1 and 3.0 points, while the miracle throw to Jermaine Kearse was also worth 3.0 points.
That same miracle throw increased the Seahawks chances of winning by 50.9%, as the Seahawks had a 34.0% chance of victory after converting a 3rd and 10 completion over Logan Ryan- a conversion worth 2.0 expected points and 22.7% in expected win percentage, the third biggest change in winning percentage in the game.
Brady's passes for 20 and 13 yards to Gronkowski were also big win changers on second down, improving the Patriots odds by 19.6% and 15.5%.
In the end, nothing can touch Butler's interception with regards to expected points or changing the odds of winning. It's truly the biggest play imaginable.