That's really not how it works. Keep in mind that average memes by non-popular users can make the front page too. If popularity were the only factor for a meme to make the front page, then all the memes of a popular user would make the front page, and there are no users on imgflip that can claim that.
It's true that the front page is hard to figure out, and sometimes memes that people would call "average" make it there, but you're just guessing when you say "just because a poster is popular," and it's not a good guess. There are probably a lot of factors that influence how people vote on memes.