BakedBeans33:
I'm in the same boat. Average score is 64 and change. I'm a T.M. C&M clothing attributes maxed out. Play a Callaway slow meter ball or the Titelist. Clubs are quality. Have 100+ ranked rounds. What is holding me back?? I've seen Legend players with high 80s averages. I'm losing my mind !!! :)
I play PC so don't know everything about mobile. On PC you need 61.000 average and 50 ranked rounds as a TM. I know on mobile, tiering up is mostly based on levels up to a certain point, since many on mobile don't play many ranked rounds.
Note that only the ranked rounds since you last tiered up count towards the average and towards the next rier (using the PC system).
WGT still holds some mysteries that they don't divulge......
Anyway, don't be in a rush. Things get harder at Legend.