My main one is:
1. No idea how players are performing during a game - a player rating during the game is a must have, that way you can make considered substitutions.
2. As others have said - games too close together - a cynical way of managers having to spend tokens to move match times maybe?
3. 1st season I had 1 friend in the same league (out of 3 at the same level) this season none, but still have bot teams in my league at level 3 - why not remove bot teams, consolidate 'real' teams and try to keep friends together whereever possible.
4. Too many injuries during games and training
5. Tranfers - better players available from scout than on the market, meaning you have to buy (with real money) tokens to buy the better players - seems game is orientated to getting players to spend as much as money as possible.