Riot: Your grading system makes no sense.
Refer to the image.
Top Game: Less kills, less CS, lost faster, was chased out of lane by Diana pretty early.
Bottom Game: Crushed Swain, took a Dragon, took a Barron; staved off the loss for quite a while.
Bottom game earned the A rank, top game earned the S rank; despite being objectively worse in EVERY single category.
[zombie-brand-facepalm]