Significantly more power and shittier footwork will lead to more knockouts. Submission numbers are dependent on how many guys in that division are really good at it. LHW and HW just simply don't have very many guys who have the mindset of primarily attacking with submissions. I would guess that LHW and HW have a much higher percentage of flash knockouts instead of TKOs as well which would impact the number of submission finishes.
Yes, the numbers show what pretty much should have been expected. Nothing surprising at all. But it's nonetheless nice to see the expectations confirmed.
Bantam weight is slightly off, but I guess that has to do with a less deep and heterogeneous distributed talent pool and consiquently higher rate of missmatchups. The rest of the weight classes show a quite linear change in fight endings.