There are a lot of very talented players in the league. Insigne for example is a world class player, and he is currently on about the same G+A per game as he was in Napoli. I can't really speak about whether he or the others dominate or not, as I didn't really watch the games, but I read a lot of posts about Puig being too good for the league.
Maybe he would dominate like this in the level of the La Liga like he did vs Atletico or Juventus or other top teams if he got the chance to play there regularly.
edit: in any way I have gotten a lot of questions on my doubts from Puig. His stamina seems to be very good, see for example how he sprinted like a maniac in min. 67 to almost anticipate a goal yesterday. His leadership and reliability seems to also be top notch, I watched only one full game with LA Galaxy, but he seems to thrive being the engine of the team, playing reliably while also progressively and creatively - he doesn't seem to be making silly mistakes and have found the right balance for when to threaten and when to circulate the ball.