I believe your stats are mixed up. Even if we take into account all matches of 2019, there is only a 18 map difference. 1500 more rounds if we were to assume no overtime would be a minimum of 50 maps. And given Astralis has a tendency to dominate or at least win before the other team reaches double digits, this is unlikely. I'm going to assume that dev1ce played 2200 rounds and s1mple played around 1500, meaning a difference of 660. Which while still a decent gap, doesn't say much. It is true that NaVi played less events, but even when they were losing s1mple was usually still in great form. If you want my honest opinion, if NaVi didn't fuck up their online qualifiers early in the year, hadn't taken a 3 month break and didn't give the awp back to GuardiaN, I believe s1mple would've been #1. I say this because Zyw0o performed very average at both majors and was barely a Top 10 player in the first 4 months of the year (statistically speaking).
All that said, Zyw0o is definitely #1, and it would've been very close between s1mple and dev1ce as it is.