How is this remotely balanced?

i am sorry but how is possible for a kalista to snowball this hard this fast over 27 kills in 20 minutes.... 2v5 our entire team. I am sorry but something is seriously wrong. Don't post that we sucked ass because it was impossible to kill kalista/raka they literally 2v5'd our entire team all game long with the rest doing whatever they wanted. Also I was winning lane, and drawing pressure from jungler. Our mid and jungler were roaming bot to try and shutdown kalista/raka but kept dying everytime.