Jack was deemed fit enough to start against Copenhagen so I'm not sure what Pep's suggesting - either our medical team missed something or Jack was able to mislead them? Both seem unlikely.
I think if there were behavioural issues then Pep would probably allude to them, he's talked about disciplinary decisions with players before. And if the club thought Jack had a drinking problem they'd have bundled him into rehab rather than simply not playing him.
He's had an underwhelming season so far because of illness, injury etc. but when he has played I've thought he often looked good.
He needs to recover from this injury, get his head straight and throw himself into training. But if Pep wants him match-fit then he's going to have to give him minutes.