Since Saban got there Alabama has only gone undefeated twice. Losing a game to A&M this year isn’t out of the norm for them, so I wouldn’t use it as evidence that they’re slipping.
What I saw this year is a team that’s pretty similar to most of his teams: one of the top two teams in the country. Rarely has his team been absolutely dominant to the point that no other team can touch him in any given year.
The difference between him and the competition is he’s pretty much always one of the top two teams, whereas the competition has rotated between Texas, Ohio State, Florida State, Auburn, Oregon, Clemson, and Georgia. He’s sustained that position for over a decade while the others come and go, with Clemson being the closest thing to it.
I don’t see this loss being any different than his other championship game losses. They’ll be right there again next year IMO, especially if they get rid of Bill O’Brien. Their offense took a step back this year because of him.