A very unscientific and quick look at the world rankings from this week in 2013 and comparing them to the current ranking shows that the leader has fewer points but the next 9 have more in 2018 than 5 years ago.
2013 top 10 points
12, 8.9, 7.3, 6.8, 6.3, 6.3, 5.7, 5.4, 5.1, 5
2018 top 10 points
10.6, 8.9, 8.4, 7.8, 7.3, 7.1, 6.6, 6, 5.9, 5.6
It loosely implies that the more players gaining more ranking points now than 5 years ago.
So it could be argued that the top 10 now is stronger than the top 10 of 5 years ago....
Or that the rest of the field is relatively weaker than 5 years ago? Statistics can very often be skewed to fit a specific viewpoint