not recieving my proper grade

There have been multiple occasions where I have outperformed my teammates in terms of more kills, less deaths, more assists, more cs, more gold, more damage dealt, more damage dealt to champions, and even more kill participation. And in most cases a combination of all of those aforementioned factors. However the problem Is my teammate who underperformed got the S rank whilst I only received an A rank. Now if there is a bug or something please let me know or if there is a hidden factor tell me. After reading the patch notes about mastery level 6 a 7 requiring S rank games I need to know why I'm not getting what I deserve as far as performance ranks. If this has something to do with receiving chests then that's understandable however, when level 6 ad 7 mastery is prerequisited by earning an S rank then S ranks cannot be limited by the number of chests one is allowed to receive in a certain period. Please someone from Riots support staff reply to this

PS. I am adding a link for my match history so that all the games can be reviewed and proven to where I am out performing my teammates. Write Your Thoughts