Problem with Getting S sometimes

Ok so im a lvl6 mastery trying to get my last S for seven and i've noticed some thing that has been frustrating at this point, that applies to any other point i have been before obtaining lvl6. When you are on a roll and dominating the game the enemy team will likely surrender, this in turn denies me the opportunity to obtain this S. I think it is u nfair in a way. yes eventually i will get it but still can there be a system to counter act this? For example, once, only once, maybe twice after a long wait like an month, you will get a mastery token if based on the data and how you played you most likely would have gotten an S or higher on multiple games were the enemy team surrendered? I feel this would solve the problem with enemy teams surrendering when you were clearly going to get an S.