djlovesyou: I just hit level 70 and my average dropped from 64.4ish to 63.5 without me actually having done anything.
As keidan said, the level has nothing to do with it.
But, you, a TM, beat a Legend in a match, and this may drop your average big time.
I once experiented -0.7. Winning credits in tournaments may also push you closer to the threshold.
It won't happen again when you're a Legend.