Hi,
The array players represents each player that we are analyzing, it is 0 for the first player and 1 for the second player.
No, psi is the probability of not scoring in a match (it is only important for the zero-inflated part of the model).
They are not off, remember that when we defined time_played as a uniform dist from 0 to 90, the average number of goals that each player scored per 90 minutes is much higher than 1 or 2 (because they played much less than 90 minutes for each of the 100 games!).