Kaaya didn’t bust.
He reached his athletic ceiling.
Kayaa was an overachiever with a pretty good and accurate arm, but well below average rest-of-body athleticism.
In college, he overcame this with hard work and a strong work ethic, hard study, and strong preparation. This made him into a very good college quarterback. But as far as the NFL, he will always be limited by his lack of athleticism and mobility.
From what I’ve seen, Tate doesn’t have half the arm Kaaya did. But I really need to see him throw more, and I have it. I’m not sure any of us here have.