Hey Eric,
I recall vision being the SUM of the lasts four years with the most reason season being weighted most. IE:
Season 200 14 wins X4 = 56
Season 199 10 wins X3 = 30
Season 198 17 wins X2 = 34
Season 197 6 wins X1 = 6
For a vision score of 126
Now the following season your wins look like:
Season 201 13 wins X4 = 52
Season 200 14 wins X3 = 42
Season 199 10 wins X2 = 20
Season 198 17 wins X1 = 17
For a vision score of 131
Notice your worst season dropped off which helped so much that even winning fewer games in 201 than 200 actually increased your vision score.
As far as the break line for vision tiers I'm unaware of those lines however, I have noticed a 7-10 point vision score increase does result in just a couple more recruits showing up. That may not seem like much help - a couple recruits here and there - but put together consistent mid-teen winning seasons and the vision score increases closer to the max of 190 (4 straight seasons of 19 wins). Conversely, I've not tested it, but I'm guessing four consecutive zero win seasons will still allow you to see the same recruits as teams with four seasons of nine or fewer wins (appx vision score of 90).
If anyone as more recent or more definitive info, please share!