1. No apparent reason for divisions
Why are they dividing teams into two divisions? Did they mention the reason anywhere? Because I really don't see the point of this. I did talk about the possibility of Blizzard having two or more divisions for the league about two months ago in one thread (https://www.over.gg/5409/overwatch-league-teams/?page=2#60), but my reasoning was to decrease the distance to travel for each team by not having to play against the teams of different regional division until playoffs. But they are not even doing that, so I don't really see what purpose this is serving. Are they planning to do that for later seasons when teams will actually have to travel around?
2. One less match against random(?) four teams
Also, five matches against the teams in same division and five matches against the teams of the other division for each stage "seems" fair, but if you think about it, this is really weird too. You have six teams in each division, so teams will have five teams to compete against in the division they are part of, but they have six teams to compete against in the division they are not part of. In the end, each team will compete with everyone except one team in different division in each stage. This might not seem like much, but this could end up giving slight advantage in the overall map score to the teams that played less games against the top teams.
For example, if you check the schedule, you can see Seoul Dynasty will not play against Philadelphia for stage 1, Boston for stage 2, Florida for stage 3, and Houston for stage 4. This means Seoul will play against these teams three times during regular season, and four times against all other teams.
So if there is a team that is playing one less match against top 4 teams, they will have advantage over a team who is playing one less match against bottom 4 teams. I don't know if this will make a huge difference, but I don't see why they can't just add one more match in each stage, so every team will compete against each other same number of matches.