double up the size of that eyeball. . coupla guys i work with looked at it and didn’t see the eye till the 2nd viewing.
For me its the acting choices that throw it towards the last third… Here’s what he does or looks like he does…
pops in walks over (Ace!)
gets frightened by a ball… autopilots into tank mode (Ace btw!!!)
then turns and faces us
steps back and he’s completely forgot about that ball he just reacted to… touches n feels it then reacts again to it with fright
steps away and is hit by another but shows no shock.
The whole acting thing feels a bit strange. Here’s what i would do and i suggest you at least block it out to see how it looks 
-pops in walks over
-gets frightened by a ball… autopilots into tank mode
-while still facing the ball his head should pop up… point the tank nose down at it so it looks like he’s looking at it.
-turn head, stand back up
-have another ball come in right to left in the foreground… then a second one come in left to right… this is his reason to step back in the way he already does… your animation is already looking like he reacts to one or two passing in the foreground 
-he steps back into the original ball he hit… in infuriation he should kick it off screen or towards camera.
-this kick of the ball triggers dozens to drop down from sky
-from there character can really panic as they fall about him and hit him on the bonce then sprint off screen.
its just an idea. It REALLY is a beautiful animation and i’m smitten with the character design and the way you’ve animated it but the acting choices feel a little ‘lost’ to me. the suggestions i made above will wrap up the piece nicely and tie in with whats happening along with adding a bit of cause n effect.
good luck - itching to see more 