Would you like some tips on how you can improve on the motion blur?

So from the looks of it, you're on the right track. The only problem is the lack of movement before and after the blur takes place. When emulating realistic motion blur, it's important that the object moves ever so slightly before the blur kicks in. I noticed how your animation has three different frames for the movement; the hand before it travels down (frame 1), the blur of the hand as it travels downward (frame 2), and the hand after it reaches the bottom (frame 3). One frame should be added between frames 1 and 2, that being the slight hand movement. In this frame, the hand should be at a *slightly* lower position than it was in frame 1. If you wanna get fancy, feel free to edit the pose as well. After this frame, you can add the blur. Of course, make sure the starting position of the blur matches up with the position of the hand in the previous frame. After this, all that's left is to add some bounce to the ending frame. This is similar to the step from the first part, except this time the hand comes

back ever so slightly from its position in the frame before it (the frame where the hand stops at the bottom).

That’s the best explanation I can give, but if you’re still confused you can watch this

and np ;)