Originally Posted by mrthundercleese
Not to be an ass, but that's called basic physics. It's not a secret to Wii Bowling.
Think about it, if the ball is spinning in the air, the air is creating essentially zero friction on the ball. The vector and velocity of the ball is going to remain roughly the same until it hits the lane. The lane will eventually create enough friction against the ball to cause the ball to slow down, and the spin will take over. If this happens halfway down the lane because you let go of the ball late, that is less chance for the ball to spin.
If you release the ball and it comes in contact with the lane at the foul line, that is more time that the ball has friction exerted against it and therefore more time for it to slow down and the spin to take over, thus determining "how much curve you will have".