He's not regressed on the pitch, no chance, when he is fit and plays he is top notch, better than he was at Barca. His so called off the field problems are vastly exaggerated too, his reyp allegation is nonsense based on that video, as was his so called punch on that Rennes fan.
As to his diving, well he's one of many divers in world football, ( look at Gabriel J yesterday ) , he just got a super bad rep because of his exaggerated rolls at the world cup.
Personally I think people are over negative on thsi guy because people love to hate Neymar (Barca fans and non-Barca fans). The price should not be a cent more than 200m and we hear the board value him at 170m so that's cool. The only concern I have is his injury record, that's a big concern.