The thing is (IMO) is for a majority of players under 60, it won't matter...i/e, even myself in the high 50's, I'd have to really tank some rounds to push my average up over 60 again, so those with 55-58 averages that are saturated (i/e could not go up before) will be in the TL Tier, just about no matter what.
In my own case if I average 64 over the next 100 rounds, I'll still be moved.
i/e...a 58 (saturated) avg Legend can shoot 100 rounds averaging 65 and still be at 59.4
The same legend would have to avg 68 over his next 100 rounds to hit a 60 avg.
This assume the previous 400 best rounds are used, plus the 100 new ones.
So, as i mentioned before, the majority of 55-58 avg's will still make TL after 100 rounds.
Of course the sub 55's will too;)