Motionsports

After much messing around and testing different methods of throwing the ball, here's what works best (for me):

Stand perfectly still. I don't mean like you've a rod in your back, but make sure not to be taking runs up or anything. Be in the same position for each throw which makes gauging power (which with no on screen indicator is pure guesswork) easier.

Next, and this is the oddest piece of advice, make your throwing action mimic that of a shotputter. Lean back on your back leg/foot. With your throwing hand at your head. Lean back a fair amount which you find comfortable, and now push forward and 'launch' the ball as you would a shotput, straight from the elbow and extending your forearm.

Don't let your arm arc downward as it would with a genuine throw of an American football, but make sure when you finish the action your arm is extended straight out and upward in front of you, pointing at the ceiling. This seems to be the best way to guarantee a consistent shot and the correct trajectory needed to hit the centre time and again.

Using this method I hit around five to six central shots in one go.