I don't think there is much wrong with Liverpool's current squad, of course the fans are waiting for a new star player to be added to the squad, maybe it could be because it would be an impressive innovation for the championship. But as you said the current squad is good enough to compete with Manchester City and Arsenal.
They look good currently but pre season games shouldn’t be what you judge a team performance by, we all saw how Chelsea played well in the pre season last season but performed woefully when the league began. Some team don’t perform well in preseason but play well when the season starts. We will see if the squad is good enough compete soon because the premier league is a league you should expect a lot from even with smaller teams they can surprise you. Let’s just hope they maintain their performance and play well when the season starts.