Champion Ratings mechanics needs to be improved.
Champion Ratings supposedly compares your match on your specific character to every other match by that specific character and then assigns a match rating depending upon your comparison to the others. However, the devs refuse to explain exactly how the mechanic works to avoid people "gaming the system". The important thing to remember also is that your end of game XP and IP is influenced slightly by your final rating and it also influences whether you receive rewards such as key fragments and chests.
That is fine, but every so often there comes a match which proves that the system is flawed. Like the match I just had. I ended 17-0-0 on a character that usually only is a support (Soraka) and it was while soloing 1v2 the entire game or 1v3 even at one point. None of my kills were "stolen" from a teammate. Every single turret and inhibitor on my lane I personally took down, I took down first blood and first turret, I captured both temple altars personally, and I personally landed the final blow on the enemy nexus. I had more gold gained at end of match than any 2 of the enemy team combined and ended with 2.4k gold more than my closest teammate.
It is indisputable that I was the MVP of that game. If I hadn't been able to hold and even dominate the bottom lane even though I was facing a 1v2 / 1v3 the entire match then the end result would have ended so very differently.
And yet when the match ended I only was awarded an A+. I did not receive a key fragment or chest obviously since it wasn't a S- or higher. I was on an IP Booster and got snubbed off of some IP, and XP, too.
...
Yeah. System needs to be fixed.
Including a screencap as proof.