Quote debaser="debaser"So the ball has forward momentum when it is being carried? '"
yes, you've got it.
Quote debaser="debaser" So it a player drops the ball straight down when running then the ball will continue moving forwards at the same pace as the player? '"
Indeed it will, though it will start to slow down due to air resistance and will start to accelerate towards the ground due to gravity. But those are external forces operating on the ball, in a vacuum and with no gravity the momentum of the ball would keep it going straight on at the same speed forward relative to the ground as it was when the player let go.
Quote debaser="debaser"I'm sorry, but I think that's rubbish. '"
What it is, is pretty basic 1st week physics.
Quote debaser="debaser"The ball has no momentum of its own until it is given some.'"
Everything has momentum. The important thing in this context is the change of momentum relative to the ground. The player has changed the momentum of the ball by accelerating it forward (relative to the ground) so yes, it has been given some additional momentum by the player.