So higher score = faster impovement.
The greyed out parts in the strategy tab are not implemented yet. Therefore your can just ignor them.
The same goes for aggression and leadership stats on your line-up
E: ah wait, were you asking for the coach performance score in your reports? That's a combination of your team elo and your league standing.
It's used for seedings in tournaments as you can see here:
https://www.lolmanager.gg/tournament