He is playing the way he’s been asked to play and doing it at a level expected of him by his manager. The fact you or anyone else wants him to play differently is neither here nor there.There’s a reason Pep mentioned him not playing as a reason we lost control against Newcastle. He is far from average and a key member of the squad.
There's no way Pep has told him "Jack, make sure whatever you do, you never contribute more than one goal or assist every month or so".
He clearly has good qualities but it's definitely possible to illustrate those without being so toothless up front. Imagine the vitriol Sterling would get if he returned the kind of output Jack does! Or Jesus or Mahrez. Four goals four assists in thirty starts is just really really bad for a forward whose side easily scores 100+ a season. And, as many, many players have proven in the past, you can offer control from the wing while also chipping in with goals and assists when the team needs them.
My problem with Jack right now is not that I think he's bad, it's that when we face the really tough defences we're effectively playing with a front two instead of a front three.