Nah the 20odd million was definitely worth it for a glorified workhorse with decent finishing. We can't create for shit against organised teams atm and Zaza would just be a more energetic Mandzukic.
We aren't guaranteed those money, it's loan with fixed fee after certain amount of appearances. Chances is they will keep Zaza out of the team to not be forced to buy him, he is persona non grata right now there.