Help me push this polymorph to b3

Polymorph seems so iffy, because it’s sort of a restriction to build around and I’m not sure how I can get the deck to perform more consistently/actually win against 4 players? It seems great in 1v1 but it’s not suited for b3 in full EDH. In b2, it’s too oppressive because you get big creatures fast and it definitely wins. It’s strange and I’m not sure how to make the deck strong but fair, so I’m wondering if I could get it to bracket 3? What GC and optimization do you guys think is needed?

https://archidekt.com/decks/26737741/kess_polymorph