He's a really impressive talent but despite the goals he still looks quite raw even against lower teams like Astana and Rochdale. That's not a criticism of him, he's 17 for god's sake but to expect him to go against premier league defences and to lead the line is expecting a lot. Even if the club had bought a cheap experienced striker in this summer, Greenwood would still have gotten a lot of games this season and it wouldn't feel so pressured.
Also, unlike Ronaldo, Rooney, Owen or Rashford at that age, his game doesn't seem to have that explosive pace and aggression either. He seems to be a finisher that needs a good team to create chances. I worry he might get a bit lost with this team around him against better opponents.
....Now watch as he probably scores 2 against Arsenal tomorrow