Mobile FIFA without pay to win, gotcha. But honestly I do like the idea and I could make this into a kind of strategy game where you build up a team with stats and can play against AI teams in tournament. I might not add all the puzzle elements like red cards as people seem to like bullying the AI but I think I can make this into a proper game! (do you think I should remove the different map and ball types though?)
I'd say it depends on what you want to go with. The different maps and ball types work with a puzzle type of game where you go through many different "stages", to keep things fresh. But if you were to go focus more on the sport angle, then yeah probably the changes on gameplay should come from the different players instead of the pitch. Hard to say though, I think it's worth trying out different concepts and seeing which feels better to move forward with.