Because silver players are very inconsistent.
That one you think is good, is probably terrible the next game. Or has no ability to adjust. If their mercy isn’t working, they can’t do anything else.
Seems like they learnt the cool movement, but forgot everything else if they’re still silver.
This happens now. But is only added or subtract based on your wins and losses. How much is added or taken away is dependent on your MMR and the lobby you’re in.