I'm a part of some really small communities (like single digit posts per month). Some of those posts are even mine. I wouldn't say that's MVP level, but...
I could be wrong, but I believe "a" is often used in African American English (which—and again, I could be wrong—I believe is the preferred term these days by linguists, rather than AAVE) even when the proceeding word begins with a vowel. Considering the guy in the picture is black and, based on the fact that he's standing in front of NBA signs, presumably American, using "a" in this meme makes sense.
If we are getting in the weeds here, the might be a more appropriate article since the most valuable is often no longer indefinite. In an AAVE context & using article ‘a/an’, I would assume “you a MVP” omitting the copula, not conjugating it like “you are a MVP”. The current expression feels uncanny.