Firstly great game - excellent game play that is both entertaining and at times massively frustrating, just like football! Rather than suggestions on game play itself, which I think is generally pretty good (bar the fact corners are more dangerous than penalties!) and seems to be developing nicely, a few ideas for touches round the edges:
I've seen this suggested previously and I think it was said it may be too complicated to calculate, but I think there could be a simple approach here.
Shots and fouls etc are obviously easy to record. The interesting one would be possession stat = the ratio of attacking decision points between the two players. I kept a rough tally on a recent game, I had 14 attacking decisions to the oppositions 7, so I would have had 67% possession
It would be a minor addition to the game, but when you've either had one of those games where you've battered the opposition but failed to score and lose on penalties, or when you've conceded without touching the ball from the kickoff, then been tackled straight away from your own kickoff and conceded again, the stats would be there in black and white to just emphasise how unfair life is!!
Competitor team rating
I'm happy with the way the leagues work, but one addition I would suggest, especially for the weekly challenges, would be to show the teams average player level. For example, my team in Arena 8 has about 6 players of level 9 and 5 of level 8, giving me an average team of 8.5. I'm not suggesting this number should influence who plays who, but it would be interesting to see what your opposition team is like, given the massive variation within an arena, with some teams filled with level 10 players and other overachieving with 6s and 7s.
Match Reward Indication
It may add some extra incentive if along with the prize money at stake being display at the top during a game, if you also knew what package was available. If you knew a diamond package was your reward for scoring that last kick volley, it would help keep the eyes on the prize!
Three points for a win
Or rather, is it time to consider you earn more cash for a win than you lose for a defeat? By all means adjust the cost of everything accordingly, but I think again it would just add a bit extra to the game
Blocking bad users, friending good users
It would be good if there was the option to block and downvote the rage quitters, or friend the person you've just had an epic 10 game battle with, so you can resume the competition at a later date!
Anyway, that's all for now.
Thanks for a great game!