Hi, I was about to do some changes in my mastery setup and wanted to put some points into precision and cruelty mastery. Can anyone, who know how these mastery works can help me to understand it. Does it help the champion critical rating, for example I am posting the image of my champ and the current critical rating stats.

If I add points to my mastery setup in precision mastery does this help to increase the critical rating mentioned in the champ stats. That is 877 as shown in the image. And the description of the mastery says that it will increase the rating by x number if I add points into this so by adding that x number does the champ stats 877 will go up ?
My question is where can I see this increase in the points of critical rating.