Does the Oakland Athletics logo misuse the apostrophe?

Solution 1:

According to the MLA Handbook, section 2.2.7:

A principal function of the apostrophe is to indicate possession. The apostrophe is also used to form ... the plurals of the letters of the alphabet (p's and q's, three A's).

So, according to MLA at least, these logos have it right.

Solution 2:

Apostrophes can be used to show omission of letters.

It can also be used to form plurals of lowercase letters.

Consider if, after abbreviating "Athletic(s)" to "A", you wanted to refer to the team in a sentence: The As won the game. One could easily misread the team name as the word "as", though that makes the sentence ungrammatical. The apostrophe clears up the ambiguity and prevents such hang-ups while reading.

_{On a side note: the abbreviation is usually paired with a definite article: Will the A's move to San Jose?}