Mystery gifts(baron steal and penta)

I'm not sure if you're asking if you personally have to get a penta kill, or if they really had to make getting a penta kill a requirement for it to unlock during MSI.

As an answer to each part:

No you don't have to score a penta personally, someone in MSI needs to get it, which Bang did achieve.

Yes something major like that had to trigger it because if it was just a double kill it would have been activated in the first game. I personally think that it was a fine requirement.

Ty @ARGRONAR :D