Didnt realize it will take so long for him, but its true, transfermarkt says:
injured until 28.09.2017
he will probably need two months to regain fitness etc so he might be available in december. Now I can see the point of buying both Costa and Berna, Pjaca probably wont participate in the first half of the season at all.
Anyway noone buys injured player so we can consider it bullshit.