Giannis is better than Robinson ever was and Giannis may not even be at his peak yet. He is a better defender. He is a better rebounder. He is a much better passer. He is a far more efficient scorer (career TS .600 to .583, but Giannis' peak is much higher and he will only expand that gap over the next several years). Like Giannis, Robinson also took a hit in the playoffs. Even the year they made the WCF, Robinson's stats were down across the board in the playoffs. And as good as Robinson's 3 year peak when he was age 28-30 was, I'd still take Giannis over the last 3 years and Giannis hasn't even theoretically reached his peak yet. Frankly, I don't think it is all that close either. Giannis is better than Robinson.
Now there are certainly some similarities but that mostly stems from them just being on teams not good enough. Middleton quite simply isn't good enough. I listed my top 25 players earlier in this thread and Middleton (nor Holiday) made it. I think there is a pretty good argument neither would be in my top 30 either as I didn't have Brown, Simmons, Morant, Murray, LaVine, Randle, Ingram, Adebayo, K. Thompson, Siakam, Westbrook, McCollum, or up and comers like Ayton, SGA, Porter in my top 25 either.
You need the top 5 player, but that guy can't be on an island all alone, and Giannis has been all alone (think Lebron in his first Cleveland stint). Again I thought adding Holiday would make a difference, but 2 games into this series he hasn't because Middleton has been a disaster. It is apparent that Middleton just isn't good enough.