The difference is this:
ZywOo has 1.28 in whole 2021, and 1.31 in big events
sh1ro has 1.25 in whole 2021, and 1.22 in big events. ZywOo without doubt put a better performance than sh1ro with almost 0.10 more rating in the biggest events of the year. There shouldn't even be a doubt that he was better than sh1ro. sh1ro can still get top2 because of his MVPs, but 2 of them were in lower tiered events, so I aren't think that.
When the difference between NiKo and Gambit duo is:
NiKo 1.21 in 2021, and 1.18 in big events
Ax1le 1.18 in 2021, and 1.18 in big events (Their rating difference is only 0.03, but in big events their rating is the SAME)
Hobbit 1.18 in 2021, and 1.16 in big events (The gap is very close, much closer than the gap between ZywOo and sh1ro).
When the gap is VERY close, then having 2 MVP is going to worth more than having 0.03 better rating.