if you looks at the ball in the air it has backspin, when Blazey catch it the the ball goes straight up, and gets spin in another direction then it had in the air,.. if the ball would touch the ground it would bounce in the direction against him and the spin on the ball would not change direction...
I don't know if you understand my genial explination but I can see that the ball bounces diffrent and has another spin than it would if it would touch the ground