I suspect but can't prove a player used cheats, should I report it?

[Stephen Lam]

@Stephen Lam favourite dont alway win. There is no cheating you been outplayed
1. Tactic
2. Player
3. Troll by the engine.
Did you make any changes in tactic formation and sub?

I used the appropriate formation and subs, as I have done from 25 seasons of learning. Favorite doesn't always win, except I was the favorite and also prepared my team to the max. I am highly doubtful that tactics was the problem, unless the game engine suddenly changed.