Dropping from 9 to 8 is not random, it doesn't matter how many minutes he player.
I don't understand this sentence. If "it doesn't matter how many minutes he play", as you say, and the shape drops... well, it's random.
Anyway I doubt this is a bug, you're very unlucky Macros. I had GS drops as well (my shapes still better than yours, though) with good minutes played. Just bad luck.