I get the feeling ARSR might not account for roles?

I am loving this game mode and I've been playing the hell out of it whenever it's up, but there's something I've noticed about it. The grades at the end haven't exactly been what I've come to expect. Most of my owned champs are supports, so that's the role I've mostly been getting. At the end of a game I'll have a score that's decent for a support: high assists and wards, low kills and cs. And I think the low kills and cs might be getting penalized? Like, last game I was playing Taric. My score at the end was 2/3/24. Like, I know that's not fantastic or anything, but I was expecting a bit higher than a B? A B+ at least. My game with Zilean at least I did get a B+ with 3/3/31.

I don't know, that's just the feeling I'm getting. Of course there's always the possibility that there just hasn't been enough games played in this mode to establish a proper average to compare to idk