Maximum to Minimum

If the minimum is A,
And the maximum is B,
And exceeding is C,
Then underachieving is me,

Overachieving to the maximum,
That would be the letter Z,
Resulting in maximum+Z to be BZ,
And underachieving is me,
So me is composed of M and E,
So anything between those,
Are underachieving,
So M becomes the minimum,
When the maximum is E,
None of this should matter,
As all should strive to be Z...

(It does make sense if followed correctly)