Our attack has underperformed this season. Not scored enough, not converted the chances. But it requires tweaking rather than major changes. Even if we didnt sign any attacking players I would expect us to score 20-30 more goals next season simply from the extra production from Jesus and Sane. I dont expect Sterling to ever be a prolific scorer, but I also expect him to steadily increase his goal scoring output. One more striker, someone like Sanchez who can also cover the wide positions would be great.
The defence is the fundamental problem, despite what the stats may say. They might not concede a huge number of goals but that's because our opponents usually only have 30% possession. In those critical games when we are put under pressure, eg at Spurs, Chelsea or Monaco, the defence crumbles.