Even if he isn't, what is there to lose. He's going to sign for another year max anyway and if it doesn't work he'll be out of the door. There's not really an awful lot of risk involved with a player that has shown over years that he can be relied on fitness-wise. If you really think he needs and will bother going out on loan to prove his fitness to us at this stage of his career you're out of your mind honestly.
There are about a million more question marks over Jack's head when it comes to that and anyway, will you be saying the same about Cazorla too when he comes back? Because I'd be worried a lot more about Cazorla's ability to contribute over Per's and the Spaniard is a lot more important to our team right now.