Say what you will about CNS's handling of Tua before the NCG, but Saban is an old school traditional, "dance with the one that brung ya" kind of guy. And, maybe up until that point, he hadn't seen enough from Tua to warrant a drastic change until the couple days that Jalen was sick.
Maybe it took all season for Tua to stop taking so many chances in practice and turning the ball over. Maybe when Tua got all the 1st team reps while Jalen had the flu, "the light came on" for him. We all know that Saban would rather have a QB that doesn't risk losing games over one that might win some, but makes too many risky mistakes.
Maybe CNS FINALLY saw Tua reign in the carelessness while Jalen was out and the reward outweighed the risks at that point.
Some of y'all doubting the highest paid coach in football with 6 championships like you know more. Ninja, please.