Why is assists so random?

Sometimes its awarded, mostly its not...

I've got to agree it's hard to tell which animations will count as assists.

I agree. I'd love to see more assists awarded. In the animation I'll see a great pass from a player that doesn't get awarded an assist, but definitely deserves it.

A corner rarely ends in a goal, but sometimes the corner kicker gets an assist. Sometimes they don't. Makes no sense.

because many things in the system sucks :D