There are so many things that I could praise when it comes to this game, but I'm sure you guys already know what are those. So I'll actually focus on potential improvements and things that need to be worked on. I don't even know whether this is even the right place to ask this question, but let's give it a shot.
1. I'm not sure if the roadmap is even available, but I was wondering if you are (somewhere along the way) looking to create an Esports/Matchmaking mod for the game?
Arenas are cool, don't get me wrong, but you need so much time to rank up considering it takes time to earn all the star points. If we, for example, had an ELO system where the game pairs you with players of similar skill level, it would be way more interesting to face each other in a ladder system.
Even though the game still has a factor of randomness, I still think it would be interesting to schedule an XYZ people tournament and see how it goes.
2. Players are improving way too slow. If you would actually reward individual players for match performance -eg. goals, assists, effective tackles it would be easier to rank up and have better players. Also a post-match screen with stats would be a great addition.
3. Case reward bonus (Free package and Goal Package) should be connected with the Arena that you're in. We get the same reward if we are on LVL 1 (100 match cost) and SUPREME (20.000 match cost). If I, hypothetically, lose 30 games in a row I will be force to play for ages until I can even afford another game. That sucks really and I see why it can drive so many players from the game and the community.
I'm currently in SUPREME arena with lvl 5 players on my team, while my opponents are on lvl 7 = my minions just get tackled to oblivion.
4. There are certain situations where the opponent tackles me in their own box (really rough, messed up foul) and the game automatically decides for "advantage" where in most situations I can't even shoot on the goal. I think that should be nerfed and if someone is spamming TACKLE like crazy throughout the court, he should also be punished if he can't plan those tackles in his own box.
SUMMARY: Mobile games are amazing when it comes to their potential and how many players CAN ACTUALLY be a part of the community and compete. It's a shame that the PC gamers (and developers) find it way more natural to create a community around the game that provides ideas and suggestions. We know that you can't implement all, but if at least something sticks from this, I'll be amazed. I used to work on ESL and Faceit mostly covering Counter Strike as an Esports title, but there are so many things and experiences that can be implemented in this community as well.
I hope that the game will be improving in that direction and that you guys will keep following community input.