Rashford in his third year, Pogba settled, Mata who was one of our better scorers is not injured, with the prospect of adding Ibra again, we're in a good position, ideally another striker will do, but with the growing talent we have it's possible they perform to a better standard than last season. Which generally is how it works with younger promising players.
Hopefully we add another striker but like I said SO FAR we have had a successful window, unless players leave it'll continue to be just that.
Edit: it's not as if we didn't create the chances, We just had a hard time putting them away, Lukaku is reliable especially vs the smaller teams, Lukaku also gives us another dynamic, someone who truly can run in behind.