They need to fix the scoring for support first. I've had games where I've gone 3-0-17 as Support and gotten an A, and times I've gone 0-2-10 and gotten an S. A lot of times I get better scores for doing worse than I normally do. Then the games I do amazing... it's like wut? Who grades this...
Plus you can pretty much get free chests by playing any ADC top, building Runann's hurricane top and doing nothing but CSing/playing defensive with 0 care for the game. Your massive creep score almost always gets you a chest if you win.