He has trained BJJ since he was 12 years old and competed in the brazilian tournaments which are notorious for being just as hard if not harder to win than the world championships/europeans because of the level of competiotions. He trains with the Minotauro twins and his brother who is a high level black belt. Walid Ismail is also a high level black belt who has high level black belt students as well. Israel does not have a good ground game. We saw this in his fight against Gastelum and Vettori. He also simply just dont have the physique for it. Costas ground game is as legit as they come. He just prefers to fuck people up standing.