Effenberg was one of the most prominent football players (Nationalmanschaft, Werder Bremen, Bayern München) beginning in the 90s, until towards the end of his sports career an escapade involving one of Lothar Matthäus' wifes was draged out and capitalised on in a "Skandal" in scandalsheets and respectable news outlets alike.
I am not usually one to nurture conspiracy myths, but FIFA has been shown before to meddle in the stakes ("alleged use of bribery, fraud and money laundering to corrupt the issuing of media and marketing rights for FIFA games", 2015 FIFA corruotion case, Wikipedia). IMHO, Stefan effin Berg could be an artist name targeted at English speaking audiences: f-ing is a productive emphatic infix and "effing" is attested in print as early as the 80s ("Oo the effing ell do you effing fink you effing are you effing sod?", New Scientist - 06. Jul 1978, pg. 45, via g-books).
The name hardly matters, except the hypothesis is showing my impression of Effenberg as a effin cool guy because he gets the women doesn't afraid of anything. Meanwhile, Matthäus was relatively old for as long as I can remember, implying he played well enough to remain recognized. He went on as a laughing stock — in no small part thanks to Stefan Raab (TV Total) — in his stint as coach for the New York Rangers and because of his many wives whose age difference is below the creepy formular (Y_xx < ½ Y_xy + 7).
Effenberg his remembrance outside of football is since influenced by some drunk public outburst and not much else. As far as the fan on the street is concerned, however, Effenberg was a player in any sense of the word.
That said, considering a former US president's indictment just this week and what the allegations are, it seems that Effenbergisierung is in full swing. Tax evasion is literally a crime on paper. Nevertheless, confident payment to a model of questionable morals, for lack of a better word, is a dogwhistle because the prevailing image of adult entertainment is dominance with black jack and hookers, with a suggestive understatement(t'is a thinker) to generate attraction to the rowdy image.
—Effenbergisierung "Meaning: A superlative of tabloidization" (@xyldke, above) already hit the nail on the head. "Tabloid" is possibly broad enough to connote as it were the vulgar. So we can understand Effenbergisierung as metonymy and sometimes more specific than that. The more recent fake-news debate underlines the problem, seeing that tableoids are the prototype of not just the irrelevant gossip and click-bait headlinese but serialized miss-information upto conspiracy theories.
PS: I am emphatically not one to speculate about conspiracy theories. I can neither confirm nor deny that the word had rather referred to "Jörg Effenberg (Direktor bei der Commerzbank, Zentraler Stab Kredit)" who is once mentioned in a Abschlussbericht 2. Untersuchungsausschuss der 13. Wahlperiode ("DDR-Vermögen"), which continued from the 13. ("Treuhandanstalt") and continued in the 14. Wahlperiode ("Parteispenden"), pressumably having attended a hearing under criminal code as witness. It is quite a stretch, and there is no indication of any wrong doing, not the least because the search suggestion "Effenberg Vermögen" which lead me to this results must refer to the player's net-worth rather than a hidden type of treasure.
It just bares mention that the Treuhandanstalt, later Bundesanstalt für vereinigungsbedingte Sonderaufgaben, is often enough considered a scam.
And sell-out is approximately matching the description, indeed. In particular, @xyldke's second example, "Boulevardisierung" of a rapper, is most definitely considered "sell-out" in Hip-Hop jargon, also as a noun. However, Stefan Effenbergs relation to tabloids was likely on the receiving end at which he would try to make the best of it, coopting the opportunity for what it's worth.
His position as a leading figure within the football cosmos may be a different matter, although rather unlikely on its own to merrit a political figure of speech.