This is not a form thing, it's an observation of some facts over the duration of his time at United and Everton.
- Relative to his actual size and muscle mass he isn't very strong at all and can be dispossessed on the ball rather easily. Harry Kane, whilst not nearly as physically imposing rarely gets dispossessed with his back to the defender.
- He has a poor touch, plain and simple. It might improve, but his ceiling as far as becoming good technically is limited. On his best day his general technical performance will be below Jesus, Aguero, Kane, on their poorer days.
- That he scores a lot of goals obscures the fact that he lacks a serious level of composure in front of goal. He doesn't possess a great variation of creativity as far as finishing is concerned. He lacks the deft speed of thought and technique to perform nuanced shots if he's closed down quickly, and consequently his shots will invariably hit the keeper or the defender will get a leg in.