I think it's a bit of a cop out blaming his poor form on the manager. We've seen numerous players over the last decade shine under awful conditions. Whether it be Greenwood, Rashford, Cavani, Shaw, Martial; hell even Januzaj, Smalling and Lukaku went through periods where they've looked quality under equally poor regimes.
It's too early to write him off of course but it's concerning to see such slow, ponderous, uncreative and quite lazy performances coming from a £70m young signing. Certainly the work ethic element you'd assume coming into a new side would be apparent. You'd especially not expect him to be conspicuously slow/lazy in comparison with our other attackers.
He needs to be given regular game time but I agree with a poster above that if he's still far off the pace come January then a 6 month loan at a team like Brentford, Leeds, Brighton etc might do him some good.
Ole's lack of ability as a manager and our awful coaching has obviously not helped, but that's a mitigating factor rather than an excuse.