At the end of the game, in addition to graphs for damage and everything. Can you add two/four maps that every player will easily tab into.
1. Your team, Highest Vision % at one point in time.
2. Other team, Highest Vision % at one point in time.
3. Your team, Lowest Vision % at one point in time (past first five minutes maybe?)
4. Other team, Lowest Vision % at one point in time.
I think having these easily access would be a good way for A. Supports to feel like they are doing well/improving (playing another game) and B. see what a big impact vision makes. We should always support vision, and I assume you can code something like %pixels/screen lit up.
Maybe exclude enemy champions/minions in the vision. But idk yet. I think the basic idea is a good start to get people more aware of it.