Yes he has called before. But.. If he was good enough then he would have broken into T1 years ago. Hes been playing in these T3 teams since 2013, the only reason hes name even comes up now by people like yourself is because you think fnatic is desperate and there are no options out there right now.
And no, robiin is not a "gamble", there is no way they sign robiin then becomes a good stable T1 team. It wouldnt be a gamble without the possibility of a pay off, just a lackluster pointless move. Dennis though would be a gamble, with potential for a pay off. We all know he is a good fragger with good crisp aim, and his calling has improved alot. And since there are no other options out there right now, I would go for that gamble. (there obviously not getting hampus-lekro-friberg)