There is something severely wrong with the way support grades are calculated
Go 3/10/14 braum? Ward everywhere and sacrifice yourself multiple times for your teammates? Nope, you get a C+.
Go 11/10/8 Lucian that didn't even build sightstone? sweet you get a S 5/1/10 kill stealing support shaco? S+ 10/4/6 support leblanc? you get a S too 12/13/18 AP blitzcrank with no sightstone OR relic shield? S ez
These games were all me playing support (troll picks were with friends). When I play proper supports, it's hard to get a S. The income/damage lost from buying sightstone/aegis/support items makes it very difficult to have good damage/be tanky enough to survive. But when I go AP blitz and ult 20 minions at once, it's easy to have gold for items, deal a crapton of damage, and ditch my teammates to die as I protobelt away. Good supports won't have good KDAs because they're the ones initiating, the ones tanking or trying to peel two tanks off the carry. They won't have good damage because they're building athenes/frozen heart/sightstone/aegis. They'll be underleveled because they spend time roaming and warding.
Riot should really reconsider the way supports are graded: damage done, deaths, and kill participation seem to be all that matter.