Styles make fights.
Nate is a cardio machine with an iron chin, plus boxing skills and a reach/height advantage, while Conor is an explosive fighter who relies on overwhelming his opponents and taking them out early, by outboxing them and controlling the distance.
You could see how that could end badly for Conor, right?
Alvarez doesn't have the chin that Nate does, the height, the reach, or the boxing. What he does have is wrestling. If Eddie pushes Conor against the fence immediately and gets past the first 2 rounds, he will win.
If he lets Conor control the distance early, he will get KO'd.