Big, clearly the rest have gotten better due to England's wealth. A clear example is a marginal club being able to sign up 4 Barca 2nd strong players. Normally, that quality of player should be heading to other teams in the top half of La Liga but they can't compete with Stoke financially for these players. This is not a club with a long and storied Premier League history. We are talking about a team from a tertiary English settlement that most European footballers were unaware of five years ago.
What this means practically for Wenger is that there are no free meals. Unlike Barca and Real, we don't have 30 games a season that should be romps. We have at most around 6 or so. This means that we need all of a high quality squad, well-considered tactics, and consistent focus to reduce variability in outputs. We are failing on all three and struggling against West Ham and Palace on consecutive weekends.
I enjoy the high levels of competition. Just hate that our manager can't keep up with the change.